Magnetic phase diagram of Li₂(Pd_1-xPt _x)₃B by ac susceptometry

The H-T phase diagram and several superconducting parameters for the noncentrosymmetric system Li₂(Pd_1-xPt_x) ₃B have been determined as a function of cation substitution x. Notably, the coherence length may be linear in platinum concentration. Despite the superconducting pairing state and band structure apparently changing fundamentally, the H-T phase diagram is essentially unchanged. Unusual aspects of the shape of the H-T phase diagram are discussed. The upper critical field H_c2(0) is not anomalously high for any Pt content, likely due to an absence of high carrier masses-in such a case, the value of H_c2(0) would not serve as a probe for novel physics.