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41.
The effect of extremely high temperatures developing on the surface during the condensation of sputtered atoms has been discovered
for the first time by direct surface temperature measurements. This temperature is considerably higher than the temperature
of the solid film beneath and proportional to the flux of atoms impinging on the surface. The surface temperature steeply
grows as the condensation starts, exists during the period of condensation, and rapidly decays after its termination. The
effect is related to the anomalously low thermal conductivity of the superficial layer that is formed by highly mobile atoms
arriving on the condensation surface. This superficial layer can be viewed as a new state of matter characterized by its anomalously
low thermal conductivity.
This text was submitted by the authors in English. 相似文献
42.
Low-temperature specific-heat measurements on YbRh2Si2 at the second order antiferromagnetic (AF) phase transition reveal a sharp peak at TN=72 mK. The corresponding critical exponent α turns out to be α=0.38, which differs significantly from that obtained within the framework of the fluctuation theory of second order phase transitions based on the scale invariance, where α?0.1. We show that under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point leading to a violation of the critical universality of the fluctuation theory. This change of the phase transition is generated by the fermion condensation quantum phase transition. Near the tricritical point the Landau theory of second order phase transitions is applicable and gives α?1/2. We demonstrate that this value of α is in good agreement with the specific-heat measurements. 相似文献
43.
Renewed interest in 3He physics has been stimulated by experimental observation of non-Fermi-liquid behavior of dense 3He films at low temperatures. Abnormal behavior of the specific heat C(T) of two-dimensional liquid 3He is demonstrated in the occurrence of a T-independent term in C(T). To uncover the origin of this phenomenon, we have considered the group velocity of transverse zero sound propagating in
a strongly correlated Fermi liquid. For the first time, it is shown that if two-dimensional liquid 3He is located in the vicinity of the quantum critical point associated with a divergent quasiparticle effective mass, the
group velocity depends strongly on temperature and vanishes as T is lowered toward zero. The predicted vigorous dependence of the group velocity can be detected in experimental measurements
on liquid 3He films. We have demonstrated that the contribution to the specific heat coming from the boson part of the free energy due
to the transverse zero-sound mode follows the Dulong-Petit Law. In the case of two-dimensional liquid 3He, the specific heat becomes independent of temperature at some characteristic temperature of a few millikelvins. 相似文献
44.
On the example of two-dimensional (2D) 3He we demonstrate that the main universal features of its experimental temperature T-density x phase diagram [see Neumann, Nyéki, and Saunders, Science 317, 1356 (2007)10.1126/science.1143607] look like those in the heavy-fermion metals. Our comprehensive theoretical analysis of the experimental situation in 2D 3He allows us to propose a simple expression for the effective mass M*(T,x), describing all the diverse experimental facts in 2D 3He in a unified manner and demonstrating that the universal behavior of M*(T,x) coincides with that observed in heavy-fermion metals. 相似文献
45.
Recently, in high-Tc superconductors (HTSC), exciting measurements have been performed revealing their physics in superconducting and pseudogap states and in normal one induced by the application of magnetic field, when the transition from non-Fermi liquid to Landau-Fermi liquid behavior occurs. We employ a theory, based on fermion condensation quantum phase transition which is able to explain facts obtained in the measurements. We also show, that in spite of very different microscopic nature of HTSC, heavy-fermion metals and 2D 3He, the physical properties of these three classes of substances are similar to each other. 相似文献
46.
We consider the behavior of quasiparticles in the superconducting state of high-Tc metals within the framework of the theory of the superconducting state based on the fermion condensation quantum phase transition. We show that the behavior coincides with the behavior of Bogoliubov quasiparticles, whereas the maximum value of the superconducting gap and other exotic properties are determined by the presence of the fermion condensate. If at low temperatures the normal state is recovered by the application of a magnetic field suppressing the superconductivity, the induced state can be viewed as a Landau-Fermi liquid. These observations are in good agreement with recent experimental facts. 相似文献
47.
48.
A theory of high-temperature superconductivity based on the combination of the fermion-condensation quantum phase transition and the conventional theory of superconductivity is presented. This theory describes maximum values of the superconducting gap, which can be as big as Δ1~0.1ε F , with ε F being the Fermi level. We show that the critical temperature 2T c ?Δ1. If the pseudogap exists above T c , then 2T*?Δ1 and T* is the temperature at which the pseudogap vanishes. A discontinuity in the specific heat at T c is calculated. The transition from conventional superconductors to high-T c ones as a function of the doping level is investigated. The single-particle excitations and their lineshape are also considered 相似文献
49.
V. R. Shaginyan A. Z. Msezane G. S. Japaridze K. G. Popov J. W. Clark V. A. Khodel 《Frontiers of Physics》2016,11(2):117102
We reveal and explain the scaling behavior of the thermopower S/T exhibited by the archetypal heavy-fermion (HF) metal YbRh2Si2 under the application of magnetic field B at temperature T. We show that the same scaling is demonstrated by different HF compounds such as β-YbAlB4 and the strongly correlated layered cobalt oxide [BiBa0.66K0.36O2]CoO2. Using YbRh2Si2 as an example, we demonstrate that the scaling behavior of S/T is violated at the antiferromagnetic phase transition, while both the residual resistivity ρ0 and the density of states, N, experience jumps at the phase transition, causing the thermopower to make two jumps and change its sign. Our elucidation is based on flattening of the single-particle spectrum that profoundly affects ρ0 and N. To depict the main features of the S/T behavior, we construct a T –B schematic phase diagram of YbRh2Si2. Our calculated S/T for the HF compounds are in good agreement with experimental facts and support our observations. 相似文献
50.
V. A. Khodel J. W. Clark V. R. Shaginyan M. V. Zverev 《Physics of Atomic Nuclei》2014,77(9):1145-1156
The nature of pairing correlations in neutron matter is re-examined. Working within the conventional approximation in which the nn pairing interaction is provided by a realistic bare nn potential fitted to scattering data, it is demonstrated that the standard BCS theory fails in regions of neutron number density, where the pairing constant λ, depending crucially on density, has a non-BCS negative sign. We are led to propose a non-BCS scenario for pairing phenomena in neutron matter that involves the formation of a hidden dineutron state. In low-density neutron matter, where the pairing constant has the standard BCS sign, two phases organized by pairing correlations are possible and compete energetically: a conventional BCS phase and a dineutron phase. In dense neutron matter, where λ changes sign, only the dineutron phase survives and exists until the critical density for termination of pairing correlations is reached at approximately twice the neutron density in heavy atomic nuclei. 相似文献