Field-induced transition within the superconducting state of CeRh <sub>2</sub> As <sub>2</sub>
Field-induced transition within the superconducting state of CeRh <sub>2</sub> As <sub>2</sub>
We report the discovery of two-phase unconventional superconductivity in CeRh$_2$As$_2$. Using thermodynamic probes, we establish that the superconducting critical field of its high-field phase is as high as 14 T, remarkable in a material whose transition temperature is 0.26 K. Furthermore, a $c$-axis field drives a transition between two different …