Physical Review B (Condensed Matter and Materials
Physics) -- October 1, 1998 --
Volume 58, Issue 14, pp. 9524-9535
Anharmonicity of flux lattices and thermal fluctuations in layered superconductors
T. Ruth Goldin and Baruch Horovitz
Department of Physics, Ben-Gurion University, Beer-Sheva 84105, Israel
(Received 19 February 1998)
We study elasticity of a perpendicular flux lattice in a layered superconductor
with Josephson
coupling between layers. We find that for flux displacements rho the energy
contains rho^2 ln rho terms,
so that elastic constants cannot be strictly defined. Instead we define
effective elastic constants by a
thermal average. The tilt moduli have terms ~ ln T which for l_J<<a,
where l_J is the Josephson length and a is the flux-line spacing, lead to
<rho^2> ~ T/|ln T|. The expansion parameter indicates that the dominant
low-temperature phase transition is either layer decoupling at high fields
(l_J>>a) or melting at low fields (l_J<<a).
©1998 The American Physical Society
PACS: 74.60.Ge, 74.80.Dm