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Numrering	Referens	Omslagsbild	Hitta
1.	Aleksandrovskii, A. N., et al. (författare) Low-temperature thermal expansion of pure and inert gas-doped fullerite C60 2003 Ingår i: Fizika Nizkikh Temperatur (Kharkov). - : AIP Publishing. - 0132-6414 .- 1816-0328. ; 29:4, s. 432-442 Tidskriftsartikel (refereegranskat)abstract The low temperature (2–24 K) thermal expansion of pure (single-crystal and polycrystalline) C60 and polycrystalline C60 intercalated with He, Ne, Ar, and Kr has been investigated using the high-resolution capacitance dilatometer. The investigation of the time dependence of the sample length variations deltaL(t) on heating by deltaT shows that the thermal expansion is determined by the sum of positive and negative contributions, which have different relaxation times. The negative thermal expansion usually prevails at helium temperatures. The positive expansion is connected with the phonon thermalization of the system. The negative expansion is caused by reorientation of the C60 molecules. It is assumed that the reorientation is of a quantum character. The inert gas impurities affect the reorientation of the C60 molecules very strongly, especially at liquid helium temperatures. A temperature hysteresis of the thermal expansion coefficient of Kr– and He–C60 solutions has been revealed. The hysteresis is attributed to orientational polyamorphous transformation in these systems.
2.	Aleksandrovskii, A. N., et al. (författare) Effect of argon on the thermal expansion of fullerite C60 at helium temperatures 2001 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics. - 1063-777X .- 1090-6517. ; 27:3, s. 245-246 Tidskriftsartikel (refereegranskat)abstract The linear thermal expansion of compacted Ar-doped fullerite C60(ArxC60) is investigated at 2–12 K using a dilatometric method. The thermal expansion of ArxC60 is also studied after partial desaturation of argon from fullerite. It is revealed that argon doping resulted in a considerable change of the temperature dependence of the thermal expansion of fullerite. An explanation of the observed effects is proposed.
3.	Aleksandrovskii, A. N., et al. (författare) Negative thermal expansion of fullerite C60 at helium temperatures 1997 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 23:11, s. 943-946 Tidskriftsartikel (refereegranskat)abstract The thermal expansion of fullerite C60 has been measured in the temperature range 2–9 K. A compacted fullerite sample with a diameter of about 6 mm and height of 2.4 mm was used. It was found that at temperatures below ~ 3.4 K the linear thermal expansion coefficient becomes negative. At temperatures above 5 K our results are in good agreement with the available literature data. A qualitative explanation of the results is proposed
4.	Aleksandrovskii, A.N., et al. (författare) On the polyamorphism of fullerite-based orientational glasses. 2005 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:5, s. 429-444 Tidskriftsartikel (refereegranskat)abstract The dilatometric investigation in the temperature range of 2–28 K shows that a first-orderpolyamorphous transition occurs in the orientational glasses based on C60 doped with H2, D2 andXe. A polyamorphous transition was also detected in C60 doped with Kr and He. It is observed thatthe hysteresis of thermal expansion caused by the polyamorphous transition (and, hence, the transitiontemperature) is essentially dependent on the type of doping gas. Both positive and negativecontributions to the thermal expansion were observed in the low-temperature phase of the glasses.The relaxation time of the negative contribution occurs to be much longer than that of the positivecontribution. The positive contribution is found to be due to phonon and libron modes, whilst thenegative contribution is attributed to tunneling states of the C60 molecules. The characteristictime of the phase transformation from the low-T phase to the high-T phase has been found for theC60–H2 system at 12 K. A theoretical model is proposed to interpret these observed phenomena.The theoretical model proposed, includes a consideration of the nature of polyamorphism inglasses, as well as the thermodynamics and kinetics of the transition. A model of noninteractingtunneling states is used to explain the negative contribution to the thermal expansion. The experimentaldata obtained is considered within the framework of the theoretical model. From the theoreticalmodel the order of magnitude of the polyamorphous transition temperature has been estimated.It is found that the late stage of the polyamorphous transformation is described well by theKolmogorov law with an exponent of n = 1. At this stage of the transformation, the two-dimensionalphase boundary moves along the normal, and the nucleation is not important.
5.	Aleksandrovskii, A.N., et al. (författare) Thermal expansion of fullerite C60 alloyed with argon and neon 2001 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - Woodbury : American Institute of Physics. - 1063-777X .- 1090-6517. ; 27:12, s. 1033-1036 Tidskriftsartikel (refereegranskat)abstract The linear thermal expansion of compacted fullerite C60 alloyed with argon (ArxC60) and neon (NexC60) are investigated by a dilatometric method. The experimental temperature is 2–12 K. In the same temperature interval the thermal expansion of ArxC60 and NexC60 are examined after partial desaturation of the gases from fullerite. It is found that Ar and Ne alloying affects the temperature dependence of the thermal expansion coefficient of C60 quite appreciably. The libration and translation contributions to the thermal expansion of pure C60 are separated. The experimental results on the thermal expansion are used to obtain the Debye temperature of pure C60. The effects observed are tentatively interpreted.
6.	Aleksandrovskii, A. N., et al. (författare) Thermal expansion of single-crystal fullerite C60 at helium temperatures 2000 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 26:1, s. 75-80 Tidskriftsartikel (refereegranskat)abstract The thermal expansion of single-crystal fullerite C60 has been studied in the range of liquid-helium temperatures (2–10 K). At temperatures below ~4.5 K the thermal expansion of fullerite C60 becomes negative, in agreement with the previous results on polycrystalline materials. A qualitative explanation of the results is proposed.
7.	Alekseeva, L. A., et al. (författare) Determination of the low-temperature self-diffusion coefficient in solid p-H-2 from creep experiments 2018 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 44:9, s. 946-951 Tidskriftsartikel (refereegranskat)abstract Dependencies of the relative elongation epsilon under the constantly applied stress at T = 1.8 K on the endurance time t of polycrystalline parahydrogen (p-H-2, similar to 0.2% of o-H-2) of high purity (99.9999 mol.%), with varying deuterium content, were measured. The region of linear dependence between the measured creep rates (epsilon) over dot of samples and the applied stress s was revealed. The conclusion that the low-temperature creep of the studied p-H-2 possesses a vacancy-type diffusion character was made on the basis of linear dependence (epsilon) over dot similar to s. Determination of the low-temperature self-diffusion coefficient of vacancies D in solid p-H-2, which characterizes the rate of low-temperature mass transfer, was performed. The cases of migration of vacancies in the crystal bulk, along boundaries separating individual crystallites, as well as between dislocations existing in crystals, are considered. A significant decrease in the (epsilon) over dot and D values with an increase in the isotope concentration in the samples was observed, while maintaining the linear relationship between (epsilon) over dot and s for the studied p-H-2. Published by AIP Publishing.
8.	Alekseeva, L.A., et al. (författare) Unusual changes in the shape of solid parahydrogen with higher than natural isotope content 2016 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 42:6, s. 484-490 Tidskriftsartikel (refereegranskat)abstract The relative elongation epsilon of samples of high purity (99.9999 mol. % with respect to nonhydrogenic impurities) parahydrogen (p-H-2, similar to 0.2% o-H-2) with different amounts of the stable hydrogen isotope deuterium is measured as a function of applied stress sigma at temperatures of 1.8-4.2 K. The samples were subjected to uniaxial tension by stepwise loading. The ratio [D]/[H] of the number [D] of deuterium atoms to the number [H] of p-H-2 hydrogen atoms ranged from 0.0055 +/- 0.0005 at. % up to 0.07 at. %. For deuterium enriched p-H-2, the easy slip dislocation stage vanished from the sigma(epsilon) curves and there was a significant reduction in the total relative elongation of the samples, as well as a substantial increase in the hardening coefficient d sigma/d epsilon. Deformation of samples of p-H-2 with deuterium contents higher than the natural amount produces an unusual change in their shape owing to the appearance of a rotational component of the low-temperature plastic mass transfer
9.	Bagatskii, M.I., et al. (författare) Low-temperature dynamics of matrix isolated methane molecules in fullerite C60 : the heat capacity, isotope effects 2014 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 40:8, s. 678-684 Tidskriftsartikel (refereegranskat)abstract The heat capacity of the interstitial solid solution (CH4)0.4C60 has been investigated in the temperature interval 1.4–120 K. The contribution of CH4 molecules to the heat capacity of the solution has been separated. The contributions of CH4 and CD4 molecules to the heat capacity of the solutions (CH4)0.40C60 and (CD4)0.40C60 have been compared. It is found that above 90 K the character of the rotational motion of CH4 and CD4 molecules changes from libration to hindered rotation. In the interval 14–35 K the heat capacities of CH4 and CD4 molecules are satisfactorily described by contributions of the translational and libration vibrations, as well as the tunnel rotation for the equilibrium distribution of the nuclear spin species. The isotope effect is due to mainly the difference in the frequencies of local translational and libration vibrations of molecules CH4 and CD4. The contribution of the tunnel rotation of the CH4 and CD4 molecules to the heat capacity is dominant below 8 K. The isotopic effect is caused by the difference between both the conversion rates and the rotational spectra of the nuclear spin species of CH4 and CD4 molecules. The conversion rate of CH4 molecules is several times lower than that of CD4 ones. Weak features observed in the curves of temperature dependencies of the heat capacity of CH4 and CD4 molecules near 6 and 8 K, respectively, are most likely a manifestation of first-order polyamorphic phase transitions in the orientational glasses of these solutions.
10.	Bagatskii, M. I., et al. (författare) Low-temperature heat capacity of fullerite C-60 doped with deuteromethane 2012 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - Melville, NY : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 38:1, s. 67-73 Tidskriftsartikel (refereegranskat)abstract The heat capacity C of fullerite doped with deuteromethane (CD4)(0.4)(C-60) has been investigated in the temperature interval 1.2-120K. The contribution Delta C-CD4 of the CD4 molecules to the heat capacity C has been isolated. It is shown that at T approximate to 120K the rotational motion of CD4 molecules in the octahedral voids of the C-60 lattice is weakly hindered. When the temperature is lowered to 80K, the rotational motion of the CD4 molecules changes from weakly hindered rotation to libration. In the range T = 1.2-30 K, Delta C-CD4 is described quite accurately by the sum of contributions from the translational and librational vibrations and tunneling rotation of CD4 molecules. The contribution of tunneling rotation to the heat capacity Delta C-CD4(T) is dominant below 5K. The effect of nuclear-spin conversion of the CD4 molecules on the heat capacity has been observed and the characteristic times for nuclear spin conversion between the lowest levels of the A- and T-species of CD4 molecules at T < 5K have been estimated. A feature observed in Delta C-CD4(T) near T = 5.5K is most likely a manifestation of a first-order phase transition in the orientational glass form of the solution. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3677237]
11.	Bagatskii, M.I., et al. (författare) The low-temperature heat capacity of fullerite C60 2015 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 41:8, s. 630-636 Tidskriftsartikel (refereegranskat)abstract The heat capacity at constant pressure of fullerite C60 has been investigated using an adiabatic calorimeter in a temperature range from 1.2 to 120 K. Our results and literature data have been analyzed in a temperature interval from 0.2 to 300 K. The contributions of the intramolecular and lattice vibrations into the heat capacity of C60 have been separated. The contribution of the intramolecular vibration becomes significant above 50 K. Below 2.3K the experimental temperature dependence of the heat capacity of C60 is described by the linear and cubic terms. The limiting Debye temperature at T → 0 K has been estimated (Θ0=84.4 K). In the interval from 1.2 to 30K the experimental curve of the heat capacity of C60 describes the contributions of rotational tunnel levels, translational vibrations (in the Debye model with Θ0=84.4 K), and librations (in the Einstein model with ΘE,lib=32.5 K). It is shown that the experimental temperature dependences of heat capacity and thermal expansion are proportional in the region from 5 to 60K. The contribution of the cooperative processes of orientational disordering becomes appreciable above 180 K. In the high-temperature phase the lattice heat capacity at constant volume is close to 4.5 R, which corresponds to the high-temperature limit of translational vibrations (3 R) and the near-free rotational motion of C60 molecules (1.5 R).
12.	Bagatskii, M.I., et al. (författare) The specific heat and the radial thermal expansion of bundles of single-walled carbon nanotubes 2012 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 38:6, s. 523-528 Tidskriftsartikel (refereegranskat)abstract The specific heat at constant pressure C(T) of bundles of single-walled carbon nanotubes (SWNTs) closed at their ends has been investigated in the temperature interval of 2–120 K. It is found that the curve C(T) has features near 5, 36, 80, and 100 K. The experimental results on the C(T) and the radial thermal expansion coefficient αR(T) of bundles of SWNTs oriented perpendicular to the sample axis have been compared. It is found that the curves C(T) and αR(T) exhibit a similar temperature behavior at T > 10 K. The temperature dependence of the Grüneisen coefficient γ(T) has been calculated. The curve γ(T) also has a feature near 36 K. Above 36 K the Grüneisen coefficient is practically independent of temperature (γ ≈ 4). Below 36 K, γ(T) decreases monotonically with lowering temperature and becomes negative at T < 6 K.
13.	Bahrova, O. M., et al. (författare) Cooling of nanomechanical vibrations by Andreev injection 2022 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 48:6, s. 476-482 Tidskriftsartikel (refereegranskat)abstract A nanoelectromechanical weak link composed of a carbon nanotube suspended between two normal electrodes in a gap between two superconducting leads is considered. The nanotube is treated as a movable single level quantum dot in which the position-dependent superconducting order parameter is induced due to the Cooper pair tunneling. We show that electron tunneling processes significantly affect the state of the mechanical subsystem. We found that at a given direction of the applied voltage between the electrodes, the stationary state of the mechanical subsystem has a Boltzmann form with an effective temperature dependent on the parameters of the device. As this takes place, the effective temperature can reach significantly small values (cooling effect). We also demonstrate that nanotube fluctuations strongly affect the dc current through the system. The latter can be used to probe the predicted effects in an experiment. Published under an exclusive license by AIP Publishing.
14.	Bahrova, O. M., et al. (författare) Entanglement between charge qubit states and coherent states of nanomechanical resonator generated by ac Josephson effect 2021 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 47:4, s. 287-293 Tidskriftsartikel (refereegranskat)abstract We considered a nanoelectromechanical system consisting of a movable Cooper-pair box qubit, which is subject to an electrostatic field, and coupled to the two bulk superconductors via tunneling processes. We suggest that qubit dynamics is related to that of a quantum oscillator and demonstrate that a bias voltage applied between superconductors generates states represented by the entanglement of qubit states and coherent states of the oscillator if certain resonant conditions are fulfilled. It is shown that a structure of this entanglement may be controlled by the bias voltage in a way that gives rise to the entanglement incorporating so-called cat-states—the superposition of coherent states. We characterize the formation and development of such states analyzing the entropy of entanglement and corresponding Wigner function. The experimentally feasible detection of the effect by measuring the average current is also considered.
15.	Balkashin, O. P., et al. (författare) Ferromagnetic resonance in copper-permalloy point contacts 2014 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 40:10, s. 929-936 Tidskriftsartikel (refereegranskat)abstract The response of copper-permalloy (Ni80Fe20) point microcontacts to microwave irradiation (8-12 GHz) is investigated systematically. The effects of the external magnetic field strength, transport current flowing through the contact, and microwave intensity and frequency on the measured signal are studied. The contributions to the contact electrical resistance owing to giant and anisotropic magnetoresistance are analyzed. The experimentally determined positions of the resonance features are in good agreement with Kittel's formula for FMR in films in parallel magnetic fields. The resonance signal is observed against the background of an additional contribution owing to rectification of the rf field on the nonlinear current-voltage characteristic of the contact. Two mechanisms for the resonance response are discovered: synchronous self-detection from mixing of the rf current with temporal variations in the resistance and a bolometric response associated with the steady-state variation in the contact resistance when magnetization precession is excited. The amplitude of the resonance signal is linearly proportional to the transport current through the contact and to the intensity of the microwave irradiation.
16.	Balkashin, O. P., et al. (författare) Nonstationary magnetization dynamics of point contacts with a single ferromagnetic film 2009 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 35:8-9, s. 693-701 Tidskriftsartikel (refereegranskat)abstract The electric conductivity of point nanocontacts between 5, 10, and 100 nm thick ferromagnetic (F) cobalt films and a nonmagnetic (N) metal (copper or silver) needle is investigated. Two fundamentally different mechanisms for the formation of the response, signal to microwave irradiation have been observed for the first time. One mechanism is due to the effect of the rectification of high frequency ac current on the nonlinearity of the current-voltage characteristics due to the precession of the magnetization under the action of a constant transport current flowing through the contact. The second one is associated with the resonance excitation of the precession of the magnetization vector at the fundamental frequency and its harmonic by an external high-frequency field. The experimental results support a previous contention that a "surface spin valve" whose static and dynamic properties are similar to conventional F-1-N-F-2 spin valve [Nano Letters 7, 927 (2007)] is formed in the experimental F-N nanocontacts.
17.	Balkashin, O. P., et al. (författare) Spin-valve effects in point contacts to exchange biased Co40Fe40B20 films 2014 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 40:10, s. 915-918 Tidskriftsartikel (refereegranskat)abstract Nonlinear current-voltage characteristics and magnetoresistance of point contacts between a normal metal (N) and films of amorphous ferromagnet (F) Co40Fe40B20 of different thickness, exchange-biased by antiferromagnetic Mn80Ir20 are studied. A surface spin valve effect in the conductance of such F-N contacts is observed. The effect of exchange bias is found to be inversely proportional to the Co40Fe40B20 film thickness. This behavior as well as other magneto-transport effects we observe on single exchange-pinned ferromagnetic films are similar in nature to those found in conventional three-layer spin-valves.
18.	Barone, A., et al. (författare) Macroscopic quantum phenomena in Josephson structures 2010 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 36:10-11, s. 876-883 Tidskriftsartikel (refereegranskat)abstract The Josephson effect is a probe with unparalleled capabilities for the study of a variety of macroscopic quantum phenomena. This is a survey of important achievements and challenging trends, in particular macroscopic quantum tunneling and energy level quantization. We focus on high-T-C superconducting structures and recent research on nanostructures.
19.	Bocharov, D., et al. (författare) Electronic structure of cubic ScF3 from first-principles calculations 2016 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 42:7, s. 556-560 Tidskriftsartikel (refereegranskat)abstract The ground state properties of cubic scandium trifluoride (ScF3) perovskite were studied using first-principles calculations. The electronic structure of ScF3 was determined by linear combination of atomic orbital (LCAO) and plane wave projector augmented-wave (PAW) methods using modified hybrid exchange-correlation functionals within the density functional theory (DFT). The comprehensive comparison of the results obtained by two methods is presented. Both methods allowed us to reproduce the lattice constant found experimentally in ScF3 at low temperatures and to predict its electronic structure in good agreement with known experimental valence-band photoelectron and F 1s x-ray absorption spectra.
20.	Borynskyi, V. Yu, et al. (författare) Thermomagnetic transition in nanoscale synthetic antiferromagnets Py/NiCu/Py 2023 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 49:7, s. 863-869 Tidskriftsartikel (refereegranskat)abstract Using the method of SQUID magnetometry, the features of the antiferromagnet-ferromagnet thermomagnetic transition in arrays of the nanosized disks of Py/NiCu/Py synthetic antiferromagnets (SAFs) have been investigated. The effective interlayer interaction in individual SAFs “ferromagnet/diluted ferromagnet/ferromagnet” (F2/f/F1) changes from high-temperature antiferromagnetic to low-temperature ferromagnetic upon the transition at the Curie temperature T C f of the interlayer f. Temperature dependence of the magnetic parameters of individual layers and their effect on the features of the thermomagnetic transition are determined. The observed properties are important for the development of temperature-controlled nanoscale SAFs and multilayer nanostructures based on them.
21.	Chung, Sunjae, et al. (författare) Magnetic droplet solitons in orthogonal spin valves 2015 Ingår i: Fizika Nizkih Temperatur. - : American Institute of Physics (AIP). - 0132-6414 .- 1816-0328. ; 41:10, s. 833-837 Tidskriftsartikel (refereegranskat)abstract We review the recent experimental advancements in the realization and understanding of magnetic droplet solitons generated by spin transfer torque in orthogonal nanocontact based spin torque nanooscillators (STNOs) fabricated on extended spin valves and spin valve nanowires. The magnetic droplets are detected and studied using the STNO microwave signal and its resistance, the latter both quasistatically and time-resolved. The droplet nucleation current is found to have a minimum at intermediate magnetic field strengths and the nature of the nucleation changes gradually from a single sharp step well above this field, mode-hopping around the minimum, and continuous at low fields. The mode-hopping and continuous transitions are ascribed to droplet drift instability and re-nucleation at different time scales, which is corroborated by time-resolved measurements. We argue that the use of tilted anisotropy fixed layers could reduce the nucleation current further, move the nucleation current minimum to lower fields, and potentially remove the need for an applied magnetic field altogether. Finally, evidence of an edge mode droplet in a nanowire is presented.
22.	Danilchenko, Boris A, et al. (författare) Self-heating of metallic carbon nanotube bundles in the regime of the Luttinger-liquid conductivity 2011 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 37:8, s. 710-717 Tidskriftsartikel (refereegranskat)abstract The conductivity of bundles of carbon single-walled nanotubes with metallic conductivity (metallic nanotubes) is investigated over the wide temperature range 4.2-330 K and electrical fields up to 50 V. The usage of short electrical pulses of the duration of 10 ns allowed to avoid an influence of a self-heating of the investigated structures on current-voltage characteristics. It is shown that the temperature dependence of conductivity is described by the power function G proportional to T(alpha). At helium temperatures the asymptotic dependence of current on applied voltage is close to J proportional to V(1+alpha) with alpha = 0.45. From comparison of the obtained results of measurements with calculations, it is shown that the conductivity of nanotube bundles is well described within the theory of the Luttinger-liquid conductivity for one-dimensional conductors. The self-heating of the carbon nanotube bundles was observed in the case of measurements in the regime of dc current. A method for determination of the self-heating temperature of nanotube bundles as a function of an applied electrical field is proposed. The power dependence of the self-heating temperature on voltage T proportional to V(p) with the exponent p = 2.1 was observed above some threshold voltage in the temperature range 4.2-200 K. Above 200 K the exponent decreased down to p = 1.35. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3662331]
23.	Dittmer, Staffan, 1970, et al. (författare) Local heating method for growth of aligned carbon nanotubes at low ambient temperature 2008 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 34:10, s. 834-838 Tidskriftsartikel (refereegranskat)abstract We use a highly localised resistive heating technique to grow vertically aligned multiwalled nanotube films and aligned single-walled nanotubes on substrates with an average temperature of less than 100oC. The temperature at the catalyst can easily be as high as 1000 oC but an extremely high temperature gradient ensures that the surrounding chip is held at much lower temperatures, even as close as 1μm away from the local heater. We demonstrate the influence of temperature on the height of multi-walled nanotube films, illustrate the feasibility of sequential growth of single-walled nanotubes by switching between local heaters and also show that nanotubes can be grown over temperature sensitive materials such as resist polymer.
24.	Dolbin, Alexander Vitoldovich, et al. (författare) Influence of dissolved oxygen on the thermal expansion and polyamorphism of fullerite C60 2007 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 33:5, s. 465-471 Tidskriftsartikel (refereegranskat)abstract The temperature dependence of the coefficient of linear thermal expansion alpha of O-2-C-60 solutions with 20% and 80% filling of the octahedral cavities with oxygen is investigated in the temperature interval 2.2-24 K. Hysteresis of alpha(T) is observed, attesting to the coexistence of two orientational glasses in these solutions. A comparison of the behavior of these glasses is made. The characteristic times for reorientation of the C-60 molecules and for the phase transformations in the solutions are determined. When the temperature of the O-2-C-60 solution with 20 mol.% oxygen is increased to 450 degrees C, a chemical interaction of the oxygen with the C-60 molecules is manifested. It proves possible to separate the influences of the chemical and physical sorption of oxygen on the thermal expansion of polycrystalline fullerite C-60.
25.	Dolbin, Alexander V., et al. (författare) Low-temperature radial thermal expansion of single-walled carbon nanotube bundles saturated with nitrogen 2010 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 36:5, s. 365-369 Tidskriftsartikel (refereegranskat)abstract The effect of a N2 impurity on the radial thermal expansion coefficient αr of single-walled carbon nanotube bundles has been investigated in the temperature interval 2.2–43 K by the dilatometric method. Saturation of nanotube bundles with N2 caused a sharp increase in the positive magnitudes of αr in the whole temperature range used and a very high and wide maximum in the thermal expansion coefficient αr(T) at T ~ 28 K. The low temperature desorption of the impurity from the N2-saturated powder of bundles of single-walled carbon nanotubes with open and closed ends has been investigated.
26.	Dolbin, Alexander V., et al. (författare) Quantum effects in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 4He 2010 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - Woodbury, N.Y. : American Institute of Physics. - 1063-777X .- 1090-6517. ; 36:7, s. 635-637 Tidskriftsartikel (refereegranskat)abstract The radial thermal expansion αr of bundles of single-walled carbon nanotubes saturated with 4He impurities to the molar concentration 9.4% has been investigated in the interval 2.5–9.5 K using the dilatometric method. In the interval 2.1–3.7 K αr is negative and is several times higher than the negative αr for pure nanotube bundles. This most likely points to 4He atom tunneling between different positions in the nanotube bundle system. The excess expansion was reduced with decreasing 4He concentration.
27.	Dolbin, Alexander V., et al. (författare) Quantum phenomena in the radial thermal expansion of bundles of single-walled carbon nanotubes doped with 3He. A giant isotope effect 2011 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 37:6, s. 544-546 Tidskriftsartikel (refereegranskat)abstract The radial thermal expansion αr of bundles of single-walled carbon nanotubes saturated with 3He up to the molar concentration 9.4% has been investigated in the temperature interval 2.1–9.5 K by high-sensitivity capacitance dilatometry. In the interval 2.1–7 K a negative αr was observed, with a magnitude which exceeded the largest negative αr values of pure and 4He-saturated nanotubes by three and two orders of magnitude, respectively. The contributions of the two He isotope impurities to the negative thermal expansion of the nanotube bundles are most likely connected with the spatial redistribution of 4He and 3He atoms by tunneling at the surface and inside nanotube bundles. The isotope effect turned out to be huge, probably owing to the higher tunneling probability of 3He atoms.
28.	Dolbin, Alexander V., et al. (författare) Radial thermal expansion of pure and Xe-saturated bundles of single-walled carbon nanotubes at low temperatures 2009 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 35:6, s. 484-490 Tidskriftsartikel (refereegranskat)abstract The radial thermal expansion coefficient alphar of pure and Xe-saturated bundles of single-walled carbon nanotubes (CNTs) is measured in the interval 2.2–120 K. The coefficient is positive above T=5.5 K and negative at lower temperatures. The experiment was done using a low-temperature capacitance dilatometer with a sensitivity of 2×10−9 cm, and the sample was prepared by compacting a CNT powder in such a way that the pressure applied oriented the nanotube axes perpendicular to the axis of the cylindrical sample. The data show that individual nanotubes have a negative thermal expansion, while the solid compacted material has a positive expansion coefficient due to expansion of the intertube volume in the bundles. Doping the nanotubes with Xe caused a sharp increase in the magnitude of alphar in the whole range of temperatures used and gave rise to a peak in the dependence alphar(T) in the interval 50–65 K. A subsequent decrease in the Xe concentration lowered the peak considerably but had little effect on the thermal expansion coefficient of the sample outside the region of the peak. The features revealed are explained qualitatively.
29.	Dolbin, Alexander V, et al. (författare) Radial thermal expansion of single-walled carbon nanotube bundles at low temperatures. 2008 Ingår i: Fizika Nizkikh Temperatur. - : AIP Publishing. - 0132-6414. ; 34:8, s. 860-862 Tidskriftsartikel (refereegranskat)abstract For the first time, the linear coefficient of radial thermal expansion is measured on a system of carbon single-walled nanotube (SWNT) bundles at low temperatures (2.2–120 K). The measurements are performed using a dilatometer with a sensitivity of 2×10−9 cm. A cylindrical sample 7 mm high and 10 mm in diameter was obtained by compressing powder. The resulting bundles of nanotubes are oriented perpendicular to the sample axis. The starting powder consisted of over 90% SWNTs with outer diameter 1.1 nm, the length varying in the range 5–30 µm. A change of sign of the radial thermal expansion coefficient at 5.5 K is observed.
30.	Dolbin, Alexander V., et al. (författare) Specific features of thermal expansion and polyamorphism in CH4 – C60 solutions at low temperatures 2007 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 33:12, s. 1068-1072 Tidskriftsartikel (refereegranskat)abstract The temperature dependence of the linear thermal expansion coefficient alpha(T) is investigated in the temperature range of 2.5 to 23 K for two different CH4-C-60 solutions in which CH4 molecules occupy 24 and 50% of the octahedral interstitial sites of the C-60 lattice. In both cases, alpha(T) exhibits hysteresis, suggesting the existence of two types of orientational glass associated with these solutions. The temperature of the first-order phase transition between these two glasses is estimated, and the behavior of these two glasses is compared. The characteristic times of thermalization tau(1), reorientation of the C-60 molecules tau(2), and of the phase transformation between the glasses tau('), are estimated for these solutions. Both the temperature dependence of alpha(T) and the characteristic thermalization time tau(1) are found to have features near the phase transition temperature, and an explanation is put forward to explain these observed features.
31.	Dolbin, Alexander V, et al. (författare) The effect of O2 impurities on the low-temperature radial thermal expansion of bundles of closed single-walled carbon nanotubes 2011 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 37:4, s. 343-346 Tidskriftsartikel (refereegranskat)abstract The effect of oxygen impurities upon the radial thermal expansion αr of bundles of closed single-walled carbon nanotubes has been investigated in the temperature interval 2.2–48 K by the dilatometric method. Saturation of bundles of nanotubes with oxygen caused an increase in the positive αr-values in the whole interval of temperatures used. Also, several peaks appeared in the temperature dependence αr(T) above 20 K. The low temperature desorption of oxygen from powders consisting of bundles of single-walled nanotubes with open and closed ends has been investigated.
32.	Dolbin, Alexander V., et al. (författare) The effect of sorbed hydrogen on low-temperature radial thermal expansion of single-walled carbon nanotube bundles 2009 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 35:12, s. 939-943 Tidskriftsartikel (refereegranskat)abstract The effect of a normal H2 impurity upon the radial thermal expansion ar of single-walled carbon nanotube (SWNT) bundles has been investigated in the interval T = 2.2–27 K using the dilatometric method. It is found that H2 saturation of SWNT bundles causes a shift of the temperature interval of the negative thermal expansion towards lower (as compared to pure carbon nanotubes) temperatures and a sharp increase in the magnitude of ar in the whole range of temperatures investigated. The low temperature desorption of H2 from a powder consisting of bundles of SWNTs, open and closed at the ends, has been investigated.
33.	Dolbin, Alexander V., et al. (författare) The effect of the noncentral impurity-matrix interaction upon the thermal expansion and polyamorphism of solid CO-C60 solutions at low temperatures 2008 Ingår i: Fizika Nizkikh Temperatur. - : AIP Publishing. - 0132-6414. ; 34:6, s. 592-598 Tidskriftsartikel (refereegranskat)abstract Orientational glasses with CO molecules occupying 26 and 90% of the octahedral interstitial sites in the C60 lattice have been investigated by the dilatometric method in a temperature interval of 2.5–22 K. At temperatures 4–6 K the glasses undergo a first-order phase transition which is evident from the hysteresis of the thermal expansion and the maxima in the temperature dependences of the linear thermal expansion coefficients a(T), and the thermalization times t1(T) of the samples. The effect of the noncentral CO–C60 interaction upon the thermal expansion and the phase transition in these glasses was clarified by comparing the behavior of the properties of the CO–C60 and N2–C60 solutions.
34.	Dolbin, Alexander V., et al. (författare) Thermal expansion of solutions of deuteromethane in fullerite C60 at low temperature : Isotopic effect 2009 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics. - 1063-777X .- 1090-6517. ; 35:3, s. 226-231 Tidskriftsartikel (refereegranskat)abstract The thermal expansion of CD4 solutions in the orientational glass C60 with molar concentration of deuteromethane 20 and 50% has been investigated in the temperature range 2.5–23 K. The orientational glass CD4–C60 undergoes a first-order phase transition in the temperature interval 4.5–55 K. This transition is manifested as hysteresis of the linear thermal expansion coefficient alpha as well as maxima in the temperature dependences alpha(T) and tau1(T), where tau1 is the characteristic thermalization time of the experimental samples. The characteristic re-orientation times of the C60 molecules and the characteristic phase transformations occurring in the experimental solutions are determined. The results of the present study are compared with the results of a similar study of the solution CH4–C60. It is concluded that tunneling rotation of the CH4 and CD4 molecules occupying interstitial positions in the fullerite C60 lattice occurs.
35.	Entin-Wohlman, O., et al. (författare) Rashba proximity states in superconducting tunnel junctions 2018 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 44:6, s. 543-551 Tidskriftsartikel (refereegranskat)abstract We consider a new kind of superconducting proximity effect created by the tunneling of "spin split" Cooper pairs between two conventional superconductors connected by a normal conductor containing a quantum dot. The difference compared to the usual superconducting proximity effect is that the spin states of the tunneling Cooper pairs are split into singlet and triplet components by the electron spin-orbit coupling, which is assumed to be active in the normal conductor only. We demonstrate that the supercurrent carried by the spin-split Cooper pairs can be manipulated both mechanically and electrically for strengths of the spin-orbit coupling that can realistically be achieved by electrostatic gates. Published by AIP Publishing.
36.	Fomenko, L.S., et al. (författare) Low temperature microhardness of Xe-intercalated fullerite C60 2005 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:5, s. 454-458 Tidskriftsartikel (refereegranskat)abstract The Vickers microhardness of Xe-intercalated polycrystalline fullerite C60 (XexC60, x~=0.35) is measured in a moderately low temperature range of 77 to 300 K. A high increase in the microhardness of the material (by a factor of 2 to 3) as compared to that of pure C60 single crystals is observed. It is shown that the step-like anomaly in the temperature dependences of the microhardness of pure C60 single crystals recorded under the orientational fcc-sc phase transition (Tc~=260 K) is also qualitatively retained for XexC60, but its onset is shifted by 40 K towards lower temperatures and the step becomes less distinct and more smeared. This behavior of H-barV(T) correlates with x-ray diffraction data, the analysis of which revealed a considerable influence of xenon interstitial atoms on the peculiar features of fullerite thermal expansion due to orientational phase transitions (see the paper by A.I. Prokhvatilov et al. in this issue).
37.	Galtsov, N. N., et al. (författare) Intercalation of fullerite C60 with N2 molecules : an investigation by X-ray powder diffraction 2007 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 33:10, s. 881-885 Tidskriftsartikel (refereegranskat)abstract The lattice parameter a of fullerite C60 intercalated with N2 molecules is investigated in the temperature interval 6–295K by x-ray diffraction. It is found that the interstitial molecular N2 has a considerable effect on both the orientational phase transition temperature Tc and the orientational glass formation temperature Tg. Hysteresis of a(T) in the Tc and Tg regions is detected, along with an abrupt change in volume over the region defining Tc. Complete intercalation of C60 with N2 molecules results in a 0.2% increase in the lattice parameter, which persists over the whole temperature range. Evidence is also obtained that the interstitial guest molecular N2 induces a slight deformation of the cubic symmetry of the C60 host lattice.
38.	Grechnev, G. E., et al. (författare) Electronic structure and bulk properties of MB6 and MB12 borides 2008 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 34:11, s. 921-929 Tidskriftsartikel (refereegranskat)abstract Ab initio band structure calculations are carried out for the higher borides MB6 and MB12. High-precision measurements of the elastic constants are performed for the compounds ZrB12, HoB12, ErB12, TmB12, LuB12, YB6 and LaB6 at low temperatures. The bulk properties of the borides are analyzed on the basis of the calculated equations of states and balanced crystal orbital overlap populations. Our calculations indicate that hexaborides with divalent metals, CaB6, SrB6, BaB6, and YbB6, are semiconductors with small energy gaps. The metallic MB6 hexaborides with trivalent M atoms are found to possess larger bulk moduli values. For dodecaborides the bulk moduli are found to be higher for MB12 with increased filling of the conduction band (ZrB12, HfB12, UB12) in comparison with M3+B12 compounds. The total energy calculations for different magnetic configurations in YbB12 point to the possibility of antiferromagnetic coupling between Yb3+ ions.
39.	Grechnev, G. E., et al. (författare) Electronic structure and magnetic properties of RNi5-xCux alloys (R=Y, La, Ce) 2006 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 32:12, s. 1140-1146 Tidskriftsartikel (refereegranskat)abstract A study is made of the electronic structure and magnetic properties of RN5-xCux alloys (R = Y, La, Ce). The influence of substitution of nickel by copper on the features of the band structure and behavior of the magnetic susceptibility of these alloys is investigated. An analysis is made of the electronic states and interactions responsible for the magnetic properties of RNi5-xCux alloys.
40.	Gurevich, A.M., et al. (författare) Low temperature heat capacity of fullerite C60 doped with nitrogen 2006 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 32:10, s. 967-969 Tidskriftsartikel (refereegranskat)abstract The heat capacity C-m of polycrystalline fullerite C-60 doped with nitrogen is measured in the temperature interval 2-13 K. The contributions to the heat capacity from translational lattice vibrations (Debyc contribution), from orientational vibrations of the C-60 molecules (Einstein contribution), and from the motion of the N-2 molecules in the octahedral cavities of the C-60 lattice are estimated. However, no indications of the first-order phase transformation detected earlier in a dilatometric investigation of the N-2-C-60 orientational glass are found (beyond the experimental error limits). A possible explanation for this fact is proposed.
41.	Ilinskaya, O. A., et al. (författare) Coulomb effects on thermally induced shuttling of spin-polarized electrons 2019 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 45:9, s. 1032-1040 Tidskriftsartikel (refereegranskat)abstract A thermally driven single-electron transistor with magnetic leads and a movable central island (a quantum dot) subject to an external magnetic field is considered. The possibility of a mechanical instability caused by magnetic exchange interactions between spin-polarized electrons in this system was studied by the density matrix method. We proved analytically that for noninteracting electrons in the dot there is no such mechanical instability. However, for finite strengths of the Coulomb correlations in the dot we numerically found critical magnetic fields separating regimes of mechanical instability and electron shuttling on the one hand and damped mechanical oscillations on the other. It was shown that thermally induced magnetic shuttling of spin-polarized electrons is a threshold phenomenon, and the dependence of the threshold bias temperature on model parameters was calculated.
42.	Ilinskaya, O. A., et al. (författare) Magnetically controlled single-electron shuttle 2015 Ingår i: Low temperature physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 41:1, s. 70-74 Tidskriftsartikel (refereegranskat)abstract A theory of single-electron shuttling in an external magnetic field in nanoelectromechanical system with magnetic leads is presented. We consider partially spin-polarized electrons in the leads and electron transport in both the Coulomb blockade regime and in the limit of large bias voltages when the Coulomb blockade is lifted. The influence of the degree of spin polarization on shuttle instability is considered. It is shown that there is certain degree of spin polarization above which the magnetic field ceases to control electron transport. In the Coulomb blockade regime the depend- ence of the threshold magnetic field, which separates the “shuttle” and vibron regimes, on the degree of polarization is evaluated. The possibility of re-entrant transitions to the shuttle phase is discussed.
43.	Ilinskaya, O. A., et al. (författare) Polaronic suppression of shuttle vibrations 2023 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 49:1, s. 75-80 Tidskriftsartikel (refereegranskat)abstract A re-entrant behavior of electron shuttling is shown to occur in a nanoelectromechanical transistor made of magnetic material where spin-polarized electrons are injected into a quantum dot with a single electron level split into two by an external magnetic field. A suppression of shuttle vibrations occurs at a certain value of a bias voltage that starts to allow for transport also through the upper energy level of the dot, while for a further increase of the voltage shuttling recovers. The effect is due to a time-dependent polaronic shift of the dot energy level, which results in a reduction of the supply of electric power to the mechanical motion.
44.	Isakina, A.P., et al. (författare) Structure and microhardness of low pressure polymerized fullerite C60 1998 Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 24:12, s. 896-903 Tidskriftsartikel (refereegranskat)abstract We have carried out low-temperature x-ray diffraction studies on C60 fullerite polymerized by low quasi-hydrostatic pressure of 1.1 GPa at T = 563 K. It is established that at room temperature in freshly prepared samples three phases mainly coexist, viz. a compressed cubic phase with the lattice parameter a = 13.94 Å, an orthorhombic O' phase with the lattice parameters a = 9.12 Å, b = 9.82 Å, c = 14.60 Å, and a rhombohedral phase of symmetry R3m with the parameters a = 9.20 Å and c = 24.27 Å. Mechanical grinding or annealing at 573 K entails depolymerization of sintered samples and restoration of the fcc structure of pristine C60. During annealing in air, intercalation of fullerite lattice by oxygen molecules occurs as well as a substantial amount of some new phase is formed, most probably with tetragonal symmetry, the chemical composition and structure of which have not been determined. The microhardness of polymerized C60 is higher than that of single crystal samples roughly four-fold at room temperature and by a factor of 2.6 at liquid nitrogen temperature. Analysis shows that polymerization and grain boundaries give contributions to the microhardness of sintered samples but we did not succeed in separating these two contributions. The temperature dependence of the microhardness of polymerized samples exhibits a jump in the vicinity of 260 K, where pristine C60 fullerite undergoes the fcc-sc phase transition. We think that this jump is due to a partial destruction of the polymerized state under indentor as a result of shear straining in inhomogeneous stress fields. Annealing of polymerized C60 at a temperature of 573 K, which restores the fcc phase, leads to a considerable decrease in microhardness, the hardness "jump" near the fcc-sc transition extends in temperature and shifts to lower temperatures
45.	Ivanov, B. A., et al. (författare) Nonstationary forced motion of domain walls in ferrimagnets near the spin compensation point 2020 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 46:8, s. 841-850 Tidskriftsartikel (refereegranskat)abstract The motion of domain walls in ferrimagnets near the sublattice spin compensation point is studied theoretically, when there is an exchange enhancement in the limiting velocity of the wall. Nonlinear regimes of high-velocity nonstationary wall motion are found. A magnet parameter region in which the collective variable approach is invalid, is detected. In this region, the wall motion is accompanied by the periodic appearance of instability with respect to the increase in spin oscillations inside the domain wall.
46.	Ivanov, Zdravko G., 1949, et al. (författare) Depairing critical currents and self-magnetic field effects in submicron YBa2Cu3O7-delta microbridges and bicrystal junctions 2004 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 30:3, s. 203-207 Tidskriftsartikel (refereegranskat)abstract We report on depairing critical currents in submicron YBa 2 Cu 3 O 7-δ microbridges. A small-angle bicrystal grain boundary junction is used as a tool to study the entrance of vortices induced by a transport current and their influence on the I-V curves. The interplay between the depairing and the vortex motion determines a crossover in the temperature dependence of the critical current. The high entrance field of vortices in very narrow superconducting channels creates the possibility of carrying a critical current close to the depairing limit determined by the S-S ′ -S nature of the small-angle grain boundary junction. © 2004 American Institute of Physics.
47.	Jonson, Mats, 1947, et al. (författare) Mechanically driven spin-orbit-active weak links 2018 Ingår i: Fizika Nizkikh Temperatur. - : AIP Publishing. - 0132-6414. ; 44:12, s. 1577-1581 Tidskriftsartikel (refereegranskat)abstract We show that new functionality of spin-orbit-active electronic weak links can be achieved by their time-dependent mechanical deformation. As an illustration we use a simple model to calculate the electronic spin current generated by rotating a bent spin-orbit-active nanowire coupled to bulk metallic leads. © Institute for Low Temperature Physics and Engineering. All rights reserved.
48.	Kadigrobov, Anatoli M., 1937, et al. (författare) Dynamics of current-induced magnetic superstructures in exchange-spring devices 2012 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 38:7, s. 626-632 Tidskriftsartikel (refereegranskat)abstract Thermoelectric manipulation of the magnetization of a magnetic layered stack in which a low-Curie temperature magnet is sandwiched between two strong magnets (exchange spring device) is considered. Controllable Joule heating produced by a current flowing in the plane of the magnetic stack (CIP configuration) induces a spatial magnetic and thermal structure along the current flow - a magnetothermal-electric domain (soliton). We show that such a structure can experience oscillatory in time dynamics if the magnetic stack is incorporated into an electric circuit in series with an inductor. The excitation of these magnetothermionic oscillations follow the scenario either of “soft” or “hard” instability: in the latter case oscillations arise if the initial perturbation is large enough. The frequency of the temporal oscillations is of the order of 105–107s–1 for current densities j∼106–107A/cm2.
49.	Kadigrobov, Anatoli M., 1937, et al. (författare) Novel laser based on magnetic tunneling 2005 Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:3, s. 352-357 Tidskriftsartikel (refereegranskat)abstract A new principle for a compact spin-based solid-state laser is proposed. It operates in the 1-100 THz regime, which is difficult to reach with small size lasers. Spin-flip processes in ferromagnetic conductors form a basis-the mechanism is due to a coupling of light to the exchange interaction in magnetically ordered conductors via the dependence of the exchange constant on the conduction electron momenta. The interaction strength is proportional to the large exchange energy and exceeds the Zeeman interaction by orders of magnitude. A giant lasing effect is predicted in a system where a population inversion has been created by injection of spin-polarized electrons from one ferromagnetic conductor into another through an intermediate tunnel region or weak link; the magnetizations of the two ferromagnets have different orientations. We show that the laser frequency will be in the range 1-100 THz if the experimental data for ferromagnetic manganese perovskites with nearly 100% spin polarization are used. The optical gain is estimated to be gopt~107 cm-1. This exceeds the gain of conventional semiconductor lasers by 3 or 4 orders of magnitude. An experimental configuration is proposed in order to solve heating problems at a relatively high threshold current density
50.	Kadigrobov, Anatoli M., 1937, et al. (författare) Photon generation in ferromagnetic point contacts 2012 Ingår i: Low temperature physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 38:12, s. 1133-1138 Tidskriftsartikel (refereegranskat)abstract We show theoretically that a significant spin accumulation can occur in electric point contacts between two ferromagnetic electrodes with different magnetizations. Under appropriate conditions an inverse population of spin-split electronic levels results in stimulated emission of photons in the presence of a resonant electromagnetic field. The intensity of the emitted radiation can be several orders of magnitude higher than in typical semiconductor laser materials for two reasons. (1) The density of conduction electrons in a metal point contact is much larger than in semiconductors. (2) The strength of the coupling between the electron spins and the electromagnetic field that is responsible for the radiative spin-flip transitions is set by the magnetic exchange energy and can therefore be very large, as suggested by Kadigrobov et al. [Europhys. Lett. 67, 948 (2004)].

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