Field-induced transition within the superconducting state of CeRh<sub>2</sub>As<sub>2</sub>.

Khim, S; Landaeta, J F; Banda, J; Bannor, N; Brando, M; Brydon, P M R; Hafner, D; Küchler, R et al. · Science · 2021

basic_science · Level V

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Abstract

Materials with multiple superconducting phases are rare. Here, we report the discovery of two-phase unconventional superconductivity in CeRh<sub>2</sub>As<sub>2</sub> Using thermodynamic probes, we establish that the superconducting critical field of its high-field phase is as high as 14 tesla, even though the transition temperature is only 0.26 kelvin. Furthermore, a transition between two different superconducting phases is observed in a <i>c</i> axis magnetic field. Local inversion-symmetry breaking at the cerium sites enables Rashba spin-orbit coupling alternating between the cerium sublayers. The staggered Rashba coupling introduces a layer degree of freedom to which the field-induced transition and high critical field seen in experiment are likely related.