A bulk 2D Pauli Limited Superconductor

We present a nearly perfect Pauli-limited critical field phase diagram for the anisotropic organic superconductor α -(ET) 2 NH 4 (SCN) 4 when the applied magnetic field is oriented parallel to the conducting layers. The critical fields ( H c 2 ) were found by use of penetration depth measurements. Because H c 2 is Pauli-limited, the size of the superconducting energy gap can be calculated. The role of spin-orbit scattering and many-body effects play a role in explaining our measurements.