摘要:

The possibility of collisionless (Landau) mechanism of attenuation of long-lived zero-point oscillations in a normal Fermi liquid is studied. Expressions are obtained for the coefficients of zero-point sound attenuation in a simple model. Limiting cases of large and small amplitudes of particle interaction are considered. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593588

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Peculiarities in the problem of surface stability of a charged bounded helium film on a metal substrate are considered. The dependence of critical instability parameters on the in-plane film size is determined. A method is proposed for observing metastable states of a charged liquid film. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593589

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The pressure dependence of the superconducting transition temperatureTc(onset) ofTl1.8Ba2.0Ca2.6Cu3.0O10+&dgr;(Tl-2223) has been measured under quasi-hydrostatic pressure (QHP) up to 5.0 GPa. TheTcincreases with increasing pressure at a relatively high rate and reaches a maximum at 255.4 K and pressure of about 4.3 GPa. This is the highestTcyet observed for any high-Tcsuperconductor. The total change inTcfrom ambient condition(Tc=129 K)to the high pressure applied can be greater than 126 K. TheTcabove 200 K was replicated several times in our experiments. The site of the maximum ofTcand the value ofdTc/dP=1.7 K/GPa(atP=0) agree with previous results obtained by D. Tristan Jover &etal; (Physica C218, 24 (1993)) and J. G. Lin &etal; (Physica C175, 627 (1991)), respectively. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593590

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The dependence of the superconducting transition temperature inGdBa2Cu3O6+&dgr;single crystals on the magnetic fieldHapplied parallel to the intercrystalline layers is studied experimentally. A nontrivial dependence of the superconducting transition temperature on the fieldHis explained by magnetic field penetration into high-Tcsingle crystals. The presence of a layered structure leads to the formation of a spatially periodic magnetic structure with a period varying discretely in fieldsH≫Hc1(Hc1is the lower critical field). Any change in the magnetic structure results in a nonmonotonic (jumpwise) dependence of the superconducting transition temperature on the fieldH.The effect is estimated numerically by using the results of calculation of the critical temperature of small samples in strong magnetic fields. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593591

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The ground-state energy of two electrons on a ring is calculated for the one-dimensional Hubbard model with positive and negative on-site interaction and for the contraction model with additive and multiplicative interaction terms. Thehc/2eperiodicity of the ground-state energy with respect to a flux &Fgr; threading the loop is derived. The periodicity may serve as an indication of superconductivity. The results are shown to be consistent with the Lieb–Wu solution for&Fgr;=0limit. In addition, the new states that were missing in the Lieb–Wu solution are derived. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593577

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A phase diagram of the vortex state of Bi-2212 single crystals in a magnetic field parallel to thec⁁-axis proposed under the assumption on the two-stage destruction of long-range vortex correlation in such crystals matches with the experimental results obtained by using different methods.1234567The intersection of the dimensional crossover lineBcr(T)with the line corresponding to violation of long-range vortex correlations in the(ab&dbgcaret;)-plane makes it possible to explain the discontinuity at the critical point of the vortex lattice melting curveTm(B).Possibilities of experimental investigation of low-temperature condensed state forB>Bcrand the temperature dependenceBcr(T)are considered. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593578

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Low-temperature resistivity&rgr;(T)of Zener ferromagnets due to the interaction between the conducting and magnetic subsystem is studied. The effective Hamiltonian is obtained by using the representation of Hubbard’s operators in terms of local pseudospins and spinless fermions. The contribution to&rgr;(T)from scattering of charge carriers by spin waves and magnetic inhomogeneities is considered. The latter are simulated by a vector field with random orientation and location of scattering center. The obtained dependence&rgr;(T)=&rgr;0+&rgr;1T3/2+&rgr;2T5/2is compared with the available experimental and theoretical results. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593579

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The specific heatCmof the magnetic subsystem of reentrant ferrimagnetsLi0.5Fe2.5−xGaxO4withx=0.9and1.2is investigated in the temperature range 1.9–22 K. It is found that, in the low-temperature region of this interval,Cmis a linear function of temperature, while the dependenceCm∼T3/2is observed forT>11 K. Possible mechanisms responsible for such a behavior are discussed. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593580

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The ferro-antiferromagnetic interface is studied by using the classical discrete model. Collinear and noncollinear magnetic configurations of the interface are considered and critical values of parameters are obtained for which a collinear–noncollinear transition takes place. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593581

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Possible types of phase transitions as well as the spectra of coupled magnetoelastic waves are studied in an easy-plane ferromagnet with a rigidly fixed face. It is shown that the presence of such mechanical boundary conditions leads to a change in the type of phase transition. The dynamic properties of the system become most interesting at the point of absolute instability of the system rather than at the phase transition point. ©1998 American Institute of Physics.

ISSN:1063-777X    

DOI:10.1063/1.593582

出版商:AIP    

年代:1998

数据来源: AIP