摘要:

Scattering of magnons by a two-dimensional topological Belavin–Polyakov soliton in an isotropic ferromagnet is studied analytically. It is shown that the problem of spin wave scattering by a soliton with an arbitrary value of the topological charge &ngr; can be analyzed completely in the longwave limit. General principles of the soliton–magnon interaction are studied, especially the relation between scattering and the behavior of the mode as the magnon wave vectorkapproaches zero. It is found that the scattering intensity has its maximum value for partial waves with the azimuthal numberm=0,±1,±2(m=&ngr;−1).Although the mode with the maximum scattering always passes to a local mode fork→0according to the general law, this fact is not crucial for the scattering intensity. In particular, the scattering intensity is stronger for a partial wave withm=−1for&ngr;=1(there is no local mode fork→0)than for a partial wave withm=+1(a local mode exists fork→0).©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593619

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Attenuation of sound wave energy in low-dimensional organic conductors with several charge carrier groups is investigated theoretically. It is shown that the existence of a Fermi surface sheet in the form of a corrugated plane affects considerably the behavior of the sound attenuation rate &Ggr; in a magnetic fieldH. Giant oscillations of &Ggr; as a function of1/H,which are not associated with quantization of charge carrier energy, are predicted. Oscillations with a period dependent on the wavelength of sound appear in a quantizing magnetic field in addition to the oscillations described by the Lifshitz–Kosevich formula. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593620

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Theoretical study of the broken symmetry phase (BSP) transition line in solid HD reveals that its anomalous features provide evidence for quantum orientational melting. The observations of unusual reentrant behavior is a consequence of the symmetry properties of the system, namely, the fact that in HD all rotational states and transitions between them are allowed, in contrast to the behavior of the homonuclear isotopesH2andD2.The systematic underestimation of the transition pressure characteristic of all theories of the BSP transition can be removed if crystal-field effects are taken into account. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593621

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A microscopic extension of the phenomenological model of double-well orientational states, viz., pentagonal and hexagonal configurations of molecules, which is widely used for describing the low-temperature phase of fulleriteC60,is proposed. A simple kinetic equation and a set of thermodynamic relations connecting the crystal lattice deformation, the concentration of orientational excitations of molecules, and temperature are derived. Basic physical properties of the low-temperature phase, including orientational glass transition, heat capacity, thermal expansion, rheological properties and damping of elastic vibrations are described on a unified basis. The conclusions of the theory are compared with the experimental data, and empirical estimates are obtained for the parameters of double-well states and the lattice–orientational interaction. It is shown that the large values of thermal expansion and acoustic damping above the orientation glass-transition temperature of fullerite are due to high-intensity lattice–orientational interaction. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593622

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:1063-777X    

DOI:10.1063/1.593690

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:1063-777X    

DOI:10.1063/1.593691

出版商:AIP    

年代:1998

数据来源: AIP

ISSN:1063-777X    

DOI:10.1063/1.593692

出版商:AIP    

年代:1998

数据来源: AIP