The specific heat oscillation in the mixed state of type II superconductors is studied theoretically when rotating field within a plane containing gap minimum and maximum. The calculations are performed microscopically by solving quasi-classical Eilenberger equation for vortex lattices. The field dependence of the oscillation amplitude can discriminate between the nodal and anisotropic gap with a finite minimum and the oscillation phase gives the gap minimum position on the Fermi surface. These also provide a way to separate out the anisotropic behavior due to the Fermi velocity.
@article{arxiv.cond-mat/0409371,
title = {How to detect gap nodes of a superconductor by angle-resolved specific heat experiment?},
author = {P. Miranovic and M. Ichioka and K. Machida and N. Nakai},
journal= {arXiv preprint arXiv:cond-mat/0409371},
year = {2007}
}