EPR and microwave-absorption studies in a new class of superconductors. Quarternary rare-earth transition metal borocarbides YPd₅B₃C_0.35 and YNi₂B₂C

Abstract

Microwave-absorption techniques have been used for investigating the superconducting behaviour of the recently discovered quarternary rare-earth transition metal borocarbide superconductors. The direct microwave absorption shows a steep drop at 23 K in YPd₅B₃C_0.35. Besides the expected drop in microwave absorption observed in YNi₂B₂C at 15.5 K, there is another drop at~23 K, the origin of which is not understood at present. We have estimated the value of the lower critical field H_c1 (~20 G at 10 K) in the two cases from magnetic-field-modulated low-field microwave-absorption measurements.