M. Ichioka et T. Tsuneto, EXCITATIONS BOUND TO A VORTEX LINE IN LAYERED SUPERCONDUCTORS, Journal of low temperature physics, 96(5-6), 1994, pp. 213-219
Using Bogoliubov-de Gennes equation, we study quasiparticle excitation
s in layered superconductors in the presence of a straight vortez line
which is parallel to the layers. The lowest bound state is shown to h
ave energy eigenvalue of the order of magnitude DELTA, the energy gap,
in contrast to the corresponding value DELTA2/E(F) when the line is p
erpendicular to the layers.