Inclusions of metastable superconducting phase of gallium in SmGa2

Abstract

The magnetization M of the SmGa₂ compound has a paramagnetic character in a wide temperature range, and a significant increase in magnetization is observed below 30 K, which indicates the formation of a magnetically ordered state. At temperatures below 5 K, a sharp feature is observed on the M(H) dependences, which is the contribution from the magnetization of superconducting submicron gallium inclusions. Analysis of the M(H) dependences measured at different temperatures below 5 K allowed us to assume the presence of two superconducting gallium phases. The critical temperature T_C = 5.9 K and the critical field H_C(0) = 560 Oe correspond to the formation of a metastable β-phase of gallium, and the critical temperature T_C = 8.4 K and the critical field H_C(0) = 1100 Oe can be associated with the formation of a thin layer of amorphous gallium on the surface of the β-phase inclusions.