排序方式: 共有31条查询结果,搜索用时 15 毫秒
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V. Dyakonov A. ?lawska-Waniewska E. Zubov V. Mikhaylov A. Szytu?a W. Bazela P. Aleshkevich K. Dyakonov H. Szymczak 《Journal of magnetism and magnetic materials》2010,322(20):3072-3079
X-ray powder diffraction, magnetization, transport and magnetic resonance measurements of nanosize La0.7Sr0.3MnO3 (LCMO) manganites have been performed. The nanosize manganites were synthesized with a co-precipitation method at different (600, 700, 800 and 1000 °C) temperatures. The crystal structure of the nanopowders obtained was determined to be perovskite-like with a rhombohedral distortion (the space group R3¯c). The average size of synthesized nanoparticles (from 17 to 88 nm) was estimated using the X-ray diffraction and low temperature adsorption of argon methods. All the nanosize manganites show ferromagnetic-like ordering. Both the Curie temperature and magnetization decrease with reducing the particle size. The decrease of magnetization is due to the disordered surface shell of particles. The disordered surface layer is a source of the surface anisotropy and is responsible for the increase of coercivity. Temperature dependences of the magnetic resonance spectra parameters have allowed obtaining information on dynamics of magnetic properties in the nanoparticle systems. The resistivity was established to become higher by reducing the particles’ size and increases to a great extent in nanoparticles with the smallest average size at low temperatures. The magnetic entropy was shown to be smaller for the small particles. Using the temperature dependence of magnetic entropy the relative cooling power of the nanosize samples studied was evaluated. 相似文献
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We both theoretically and numerically investigate conditions of the stable balance between competing processes of the Raman self-frequency shift and bandwidth-limited amplification of the periodical cnoidal waves. The dependencies of the initial wave form-factor and frequency shift necessary for the stable balance on the parameter describing degree of localisation of the wave energy are presented. 相似文献
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G. A. Petrakovskiĭ L. N. Bezmaternykh O. A. Bayukov M. A. Popov J. Schefer C. Neidermayer P. Aleshkevich R. Szymczak 《Physics of the Solid State》2007,49(7):1315-1320
This paper reports on the results of measurements of the magnetic susceptibility, heat capacity, neutron scattering, muon spin relaxation, and electron paramagnetic resonance in Cu3B2O6 for the study of the ground state of the spin system of this compound. The results obtained suggest that, at a temperature of 10 K, the spin subsystem of the crystal, which consists of single spins and clusters of pairs and fours of spins interacting with one another, undergoes a transition to a state representing a superposition of the singlet (for clusters) and magnetically ordered (for single spins) states. 相似文献
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V. A. Aleshkevich A. V. Grigor’ev N. G. Uvarov 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(12):1608-1611
The problem of the propagation of a short pulse in fused silica has been considered in the vectorial approach at the free-electron
plasma density below the breakdown threshold. For the first time, the noncompensated electric charge responsible for the considerable
amplification of the longitudinal field component and superbroadening of the spectrum has been taken into account. 相似文献