5 research outputs found
Anisotropic superconductivity mediated by phonons in layered compounds with weak screening effect
Anisotropic pairing interactions mediated by phonons are examined in layer
systems. It is shown that the screening effects become weaker when the layer
spacing increases. Then the anisotropic components of the pairing interactions
increase with the screening length since the momentum dependence changes. As a
result, various types of anisotropic superconductivity occur depending on the
parameter region. For example, p-wave superconductivity occurs when the
short-range part of Coulomb repulsion is strong and the layer spacing is large.
Two kinds of inter-layer pairing may occur when the layer spacing is not too
large. Although the phonon contribution to the d-wave pairing interaction is
weaker than the p-wave interaction, it increases with the layer spacing.
Relevance of the present results to organic superconductors, high-T_c cuprates,
and Sr_2RuO_4 is discussed.Comment: 8 pages, 5 figures, (Latex, revtex.sty, epsf.sty
Spin fluctuations in nearly magnetic metals from ab-initio dynamical spin susceptibility calculations:application to Pd and Cr95V5
We describe our theoretical formalism and computational scheme for making
ab-initio calculations of the dynamic paramagnetic spin susceptibilities of
metals and alloys at finite temperatures. Its basis is Time-Dependent Density
Functional Theory within an electronic multiple scattering, imaginary time
Green function formalism. Results receive a natural interpretation in terms of
overdamped oscillator systems making them suitable for incorporation into spin
fluctuation theories. For illustration we apply our method to the nearly
ferromagnetic metal Pd and the nearly antiferromagnetic chromium alloy Cr95V5.
We compare and contrast the spin dynamics of these two metals and in each case
identify those fluctuations with relaxation times much longer than typical
electronic `hopping times'Comment: 21 pages, 9 figures. To appear in Physical Review B (July 2000
The superconducting ferromagnet UCoGe
The correlated metal UCoGe is a weak itinerant ferromagnet with a Curie
temperature T_C = 3 K and a superconductor with a transition temperature T_s =
0.6 K. We review its basic thermal, magnetic - on the macro and microscopic
scale - and transport properties, as well as the response to high pressure. The
data unambiguously show that superconductivity and ferromagnetism coexist below
T_s = 0.6 K and are carried by the same 5f electrons. We present evidence that
UCoGe is a p-wave superconductor and argue that superconductivity is mediated
by critical ferromagnetic spin fluctuations.Comment: 19 pages; review paper; accepted for publication in the Journal of
Low Temperature Physics (Special issue: Quantum Phase Transitions 2010