Discovery of magnetic phase transitions in heavy-fermion superconductor CeRh${}_2$As${}_2$

We report on the specific heat studies performed on a new generation of CeRh${}_2$As${}_2$ single crystals. Superior quality of the samples and dedicated experimental protocol allowed us to observe an antiferromagnetic-like behavior in the normal state and to detect the first-order phase transition of magnetic origin within the superconducting state of the compound. Although in the available literature the physical behavior of CeRh${}_2$As${}_2$ is most often described with the use of quadrupole density wave scenario, we propose an alternative explanation using analogies to antiferromagnetic heavy-fermion superconductors CeRhIn${}_5$ and Ce${}_2$RhIn${}_8$.