The sine-wave like d-wave superconductivity in high magnetic fields

We study a possible sine-wave like superconducting state a la Fulde-Ferrell and Larkin-Ovchinikov(FFLO) for parameters appropriate for a high-T-c cuprates YBCO and find this novel state is realizable for T less than or equal to 0.4T(c) and in a magnetic field in the a-b plane in excess of 200 Tesla. The upper critical field H-c2(theta, t) depends on theta, the angle B makes from the a axis and the reduced temperature t. In FFLO state a) H-c2(theta, t) increases almost linearly with t in decreasing temperature, b) H-c2(theta, t) and H-c2(pi/4, t) cross each other around t = 0.1.