| 11. |
- Fomenko, L.S., et al.
(författare)
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Low temperature microhardness of Xe-intercalated fullerite C60
- 2005
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:5, s. 454-458
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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).
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| 12. |
- Galtsov, N. N., et al.
(författare)
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Intercalation of fullerite C60 with N2 molecules : an investigation by X-ray powder diffraction
- 2007
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : American Institute of Physics (AIP). - 1063-777X .- 1090-6517. ; 33:10, s. 881-885
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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.
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| 13. |
- Grechnev, G. E., et al.
(författare)
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Electronic structure and bulk properties of MB6 and MB12 borides
- 2008
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 34:11, s. 921-929
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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.
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| 14. |
- Grechnev, G. E., et al.
(författare)
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Electronic structure and magnetic properties of RNi5-xCux alloys (R=Y, La, Ce)
- 2006
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 32:12, s. 1140-1146
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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.
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| 15. |
- Gurevich, A.M., et al.
(författare)
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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
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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.
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| 16. |
- Kadigrobov, Anatoli M., 1937, et al.
(författare)
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Novel laser based on magnetic tunneling
- 2005
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:3, s. 352-357
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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
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| 17. |
- Krive, Ilya V., et al.
(författare)
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Carbon "peapods" - a new tunable nanoscale graphitic structure (Review)
- 2006
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 32:10, s. 887-905
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Tidskriftsartikel (refereegranskat)abstract
- We consider the electronic properties of empty single-wall nanotubes (SWNT) and SWNT filled with fullerene molecules (carbon "nano-peapods"). The first part of the review (See. 11) is devoted mostly to the Luttinger liqued properties of individual metallic SWNT coupled to metallic electrodes or to superconducting leads. The discovery of carbon "nano-peapods" and their elastic, electric and thermal properties are reviewed in the second part of the paper (See. 111). We suggest in particular how fullerene and metallofullerene molecules can be released from a "nano-peapod" by a purely electrostatic method. (c) 2006 American Institute of Physics.
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| 18. |
- Kroon, Lars, et al.
(författare)
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Bifurcation picture and stability of the gap and out-gap discrete solitons
- 2007
-
Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 33:5, s. 481-483
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of a quaternary fragment of a discrete system of coupled nonlinear oscillators with modulated frequency parameters is investigated, and the stability of its gap and out-gap soliton-like excitations is studied.
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| 19. |
- Manzhelii, V.G., et al.
(författare)
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Thermal expansion and polyamorphism of N2 – C60 solutions
- 2006
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Ingår i: Low Temperature Physics. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 32:7, s. 695-699
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Tidskriftsartikel (refereegranskat)abstract
- The linear coefficients alpha(T) of N-2-C-60 solutions with 9.9% and 100% of the C-60 lattice thermal expansion interstitials filled with N-2 are investigated in the interval 2.2-24 K. The dependence alpha(T) has a hysteresis suggesting co-existence of two types of orientational glasses in these solutions. The features of the glasses are compared. The characteristic times of phase transformations in the solutions and reorientation of C-60 molecules are estimated.
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| 20. |
- Pluzhnikov, V. B., et al.
(författare)
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Pressure effect on the Fermi surface and electronic structure of LuGa3 and TmGa3
- 2005
-
Ingår i: LOW TEMPERATURE PHYSICS. - : AIP Publishing. - 1063-777X .- 1090-6517. ; 31:3-4, s. 313-
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Tidskriftsartikel (refereegranskat)abstract
- The Fermi surfaces and cyclotron masses of LuGa3 and TmGa3 compounds are Studied by means of the de Haas-van Alphen effect, technique under pressure. Highly anisotropic pressure dependences of the de Haas-van Alphen frequencies and cyclotron masses are observed ill both compounds. Concurrently, ab initio calculations of the volume-dependent band structures are been carried out for these compounds, including the ferromagnetic-configuration phase of TmGa3, by employing a relativistic version of the full-potential linear muffin-tin orbital method within the local spin-density approximation. The experimental data are analyzed oil the basis of the calculated volume-dependent hand structures and compared with the corresponding pressure effects in the isostructural compound ErGa3.
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