27 research outputs found
Similarity and contrasts between thermodynamic properties at the critical point of liquid alkali metals and of electron-hole droplets
The recent experimental study by means of time-resolved luminescence
measurements of an electron-hole liquid (EHL) in diamond by Shimano et al.
[Phys. Rev. Lett. 88 (2002) 057404] prompts us to compare and contrast critical
temperature T_c and critical density n_c relations in liquid alkali metals with
those in electron-hole liquids. The conclusion drawn is that these systems have
similarities with regard to critical properties. In both cases the critical
temperature is related to the cube root of the critical density. The existence
of this relation is traced to Coulomb interactions and to systematic trends in
the dielectric constant of the electron-hole systems. Finally a brief
comparison between the alkalis and EHLs of the critical values for the
compressibility ratio Z_c is also given
Linear response function around a localized impurity in a superconductor
Imaging the effects of an impurity like Zn in high-Tc superconductors [Nature
61 (2000) 746] has rekindled interest in defect problems in the superconducting
phase. This has prompted us here to re-examine the early work of March and
Murray [Phys. Rev. 120 (1960) 830] on the linear response function in an
initially translationally invariant Fermi gas. In particular, we present
corresponding results for a superconductor at zero temperature, both in the s-
and in the d-wave case, and mention their direct physical relevance in the case
when the impurity potential is highly localized