Numerical calculations of the spin polarized superconducting gap equation
Abstract
Discovery of coexistence of superconductivity with weak feromagnetism in metals such as URhGe and ZrZn2 has led to renewed interest in the microscopic theory of such systems. We have developed a method to numerically solve the spin polarized Bogoliubov  de Gennes (BdG) superconducting gap equation for arbitrary Fermi surfaces. These solutions are then used to investigate the affects of the shape of various Fermi surfaces on nonzero momentum singlet FuldeFerrellLarkinOvchinnikov (FFLO) pairing. The selfconsistent BdG gap equation is derived from a Hamiltonian that includes a Zeeman splitting term as well as the standard kinetic energy and a singlet pairing potential. Since we are numerically solving the gap equation, we can work with arbitrary dispersion relationships and multiple bands. These dispersion relationships can be taken from electronic structure calculations or from some analytic model. For a given exchange splitting and gap, the optimum pair momentum and pairing potential is found. Calculations for a number of Fermi surfaces illustrate how the shape of the Fermi surface (viz. flat portions) affects the tendency to form FFLO states.
 Publication:

APS March Meeting Abstracts
 Pub Date:
 March 2004
 Bibcode:
 2004APS..MARP13003K