| 1. |
- Andreeva, M. A., et al.
(författare)
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Magnetic ordering in a [Fe/Co](35) BCC film studied by nuclear resonant reflectometry
- 2007
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Ingår i: Journal of Experimental and Theoretical Physics. - 1063-7761 .- 1090-6509. ; 104:4, s. 577-585
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Tidskriftsartikel (refereegranskat)abstract
- An analysis of the angular dependences of nuclear resonant reflectivity time spectra for different models of magnetic ordering in films reveals an ambiguity in the magnetization direction determined from spectra measured at one orientation of the sample. This analysis explains features in the spectra of the nuclear resonant reflectivity from a MgO/[Fe(6 ML)/Co(3 ML)]35/V (1 nm) film measured before and after sample rotation by 90° about the normal to the surface. It is shown that the spectrum measured only at one orientation of the sample determines only the effective azimuth angle of magnetization γeff. This does not exclude the occurrence of a domain structure, while the angle γeff does not correspond to the true direction of the preferred orientation of magnetization. The results of measurements at two orientations of the sample can be satisfactorily matched using a model that considers a coherent mixture of states with magnetization directed along the 〈110〉 axis (77%) and with a chaotic orientation of the magnetic hyperfine field B hf in the film plane for the other nuclei.
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| 2. |
- Dvinskikh, Sergey V., et al.
(författare)
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Cross-polarization with radio-frequency field phase and amplitude modulation under magic-angle spinning conditions
- 2006
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Ingår i: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1063-7761 .- 1090-6509. ; 102:1, s. 91-101
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Tidskriftsartikel (refereegranskat)abstract
- Nucleus cross-polarization technique in a rotating frame of reference is analyzed as applied to NMR experiments with sample magic-angle spinning. The concept of simultaneous phase and amplitude modulation is suggested. According to this suggestion, the form of the Hamiltonian of recoupled dipolar interaction remains unchanged if phase inversion is accompanied by inversion of the difference of radio-frequency (RF) field amplitudes. A theoretical treatment is given in terms of the average Hamiltonian theory. The concept is demonstrated experimentally and by numerical analysis for several particular cases. Periodic phase inversion in cross-polarization experiments was shown to have the practically important advantage of suppressing chemical shift interactions and the effect of inaccurate tuning of RF field parameters.
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| 3. |
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| 4. |
- Kislinskiǐ, Yu V., et al.
(författare)
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Magnetically Dependent Superconducting Transport in Oxide Heterostructures with an Antiferromagnetic Layer
- 2008
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Ingår i: Journal of Experimental and Theoretical Physics. - 1090-6509 .- 1063-7761. ; 106:4, s. 800-805
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Tidskriftsartikel (refereegranskat)abstract
- The superconducting current in hybrid superconducting structuresNb/Au/Ca1−xSrxCuO2/YBa2Cu3O7 –δwith an antiferromagnetic layer is experimentally shown to have aJosephson nature, and the deviation from the sinusoidal dependence of the superconducting current on thephase difference between superconducting electrodes is about 20% of the second harmonic. These heterostructuresare found to have sensitivity to an applied magnetic field that is much higher than that of conventionalJosephson junctions. The experimental shape of the magnetic-field dependence of the critical current in the heterostructuresdiffers from the usual Fraunhofer shape by oscillation with a significantly smaller period along amagnetic field.PACS numbers: 74.45.+c, 74.50.+r, 75.70.Cn
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| 5. |
- Lozovik, Yu. E., et al.
(författare)
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Bose condensation of two-dimensional dipolar excitons : Simulation by the quantum Monte Carlo method
- 2008
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Ingår i: Journal of Experimental and Theoretical Physics. - 1063-7761 .- 1090-6509. ; 106:2, s. 296-315
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Forskningsöversikt (refereegranskat)abstract
- The Bose condensation of two-dimensional dipolar excitons in quantum wells is numerically studied by the diffusion Monte Carlo simulation method. The correlation, microscopic, thermodynamic, and spectral characteristics are calculated. It is shown that, in structures of coupled quantum wells, in which low-temperature features of exciton luminescence have presently been observed, dipolar excitons form a strongly correlated system.
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| 6. |
- Mendonca, J T, et al.
(författare)
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A kinetic approach to Bose-Einstein condensates : self-phase modulation and Bogoliubov oscillations
- 2005
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Ingår i: Journal of Experimental and Theoretical Physics. - New York : Maik Nauka/Interperiodica. - 1063-7761 .- 1090-6509. ; 101:5, s. 942-948
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Tidskriftsartikel (refereegranskat)abstract
- A kinetic approach to Bose-Einstein condensates (BECs) is proposed based on the Wigner-Moyal equation (WME). In the semiclassical limit, the WME reduces to the particle-number conservation equation. Two examples of applications are (i) a self-phase modulation of a BE condensate beam, where we show that part of the beam is decelerated and eventually stops as a result of the gradient of the effective self-potential, and (ii) the derivation of a kinetic dispersion relation for sound waves in BECs, including collisionless Landau damping.
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| 7. |
- Ovsyannikov, Gennady, 1948, et al.
(författare)
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Magnetotransport characteristics of strained La0.7Sr0.3MnO3 epitaxial manganite films
- 2009
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Ingår i: Journal of Experimental and Theoretical Physics. - 1090-6509 .- 1063-7761. ; 108:1, s. 48-55
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Tidskriftsartikel (refereegranskat)abstract
- The electrical and magnetic characteristics of La0.7Sr0.3MnO3 (LSMO) epitaxial manganite films are investigated by different methods under conditions when the crystal structure is strongly strained as a result of mismatch between the lattice parameters of the LSMO crystal and the substrate. Substrates with lattice parameters larger and smaller than the nominal lattice parameter of the LSMO crystal are used in experiments. It is shown that the behavior of the temperature dependence of the electrical resistance for the films in the low-temperature range does not depend on the strain of the film and agrees well with the results obtained from the calculations with allowance made for the interaction of electrons with magnetic excitations in the framework of the double-exchange model for systems with strongly correlated electronic states. Investigations of the magneto- optical Kerr effect have revealed that an insignificant (0.3%) orthorhombic distortion of the cubic lattice in the plane of the NdGaO3(110) substrate leads to uniaxial anisotropy of the magnetization of the film, with the easy-magnetization axis lying in the substrate plane. However, LSMO films on substrates (((LaAlO3)(0.3)+(Sr2AlTaO6)(0.7))(001)) ensuring minimum strain of the films exhibit a biaxial anisotropy typical of cubic crystals. The study of the ferromagnetic resonance lines at a frequency of 9.76 GHz confirms the results of magnetooptical investigations and indicates that the ferromagnetic phase in the LSMO films is weakly inhomogeneous.
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| 8. |
- Shanina, B D, et al.
(författare)
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Magnetism of palladium clusters in nanoporous carbon
- 2009
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Ingår i: Journal of Experimental and Theoretical Physics. - : MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC.. - 1063-7761 .- 1090-6509. ; 109:4, s. 609-18
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Tidskriftsartikel (refereegranskat)abstract
- To determine the electronic properties of metal-carbon clusters, palladium clusters are introduced into nanoporous carbon samples. The structural and magnetic properties of the nanocomposite thus obtained are investigated. A ferromagnetic resonance (FMR) component is observed in the electron spin resonance (ESR) spectra measured in a wide temperature range. The electron density of states (DOS) of clusters consisting of a palladium atom surrounded by carbon atoms is calculated, and it is shown that, due to the interaction between electronic terms of carbon and metal, such a cluster should exhibit magnetism. The investigation of the structures of the porous skeleton of nanoporous carbon and of palladium clusters has allowed us to reveal how carbon and palladium atoms are brought into close contact so that to give rise to the observed ferromagnetism.
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| 9. |
- Vekilov, Y. K., et al.
(författare)
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Ferromagnetism in quasicrystals : Symmetry aspects
- 2005
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Ingår i: Journal of Experimental and Theoretical Physics. - : Pleiades Publishing Ltd. - 1063-7761 .- 1090-6509. ; 100, s. 1127-
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Tidskriftsartikel (refereegranskat)
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| 10. |
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