Anisotropic magnetotransport properties of the heavy-fermion superconductor CeRh${}_2$As${}_2$

Abstract

We report anisotropic resistivity measurements of the heavy-fermion superconductor CeRh${}_2$As${}_2$ in magnetic fields up to 16 T and temperatures down to 0.35 K. The measured CeRh${}_2$As${}_2$ resistivity shows a signature corresponding to the suggested quadrupole density wave order state at $T_0\sim$ 0.5 K for both measured directions. For a magnetic field applied along the tetragonal $a$ axis, $T_0$ is enhanced with magnetic field reaching $\sim$1.75 K at 16 T. Further, a magnetic field-induced transition occurs at $B_m\sim$ 8.1 T corresponding to a change to a new broken symmetry state. For a magnetic field applied along the $c$ axis, $T_0$ is suppressed below our base temperature $\sim$0.35 K by $B\sim$ 4.5 T, a field close to the previously reported field-induced transition within the superconducting state suggested to be from an even-parity to an odd-parity state. Our results indicate that the multiple superconducting phases in CeRh${}_2$As${}_2$ are intimately tied to the suppression of the proposed quadrupole-density-wave phase at $T_0$.

6 pages and 5 figures