Superconductivity, Fermi surface topology, and structural transitions: insights from high-pressure studies of the kagome CeRu₂

CeRu₂ crystallizes in a cubic Laves phase with Ru forming a Kagome sublattice with an ambient pressure T_c of 6.1 K. To investigate further the superconductivity and possible Fermi surface topology change of this intriguing material, we systematically investigated the effects of external pressure up to 1.3 GPa for magnetization measurements, and up to ~ 170 GPa for electrical transport and X-ray measurements (XRD). The resulting phase diagram from these measurements gives insight into the interplay between the superconductivity and the Fermi surface topology. The T_c decreases linearly from 6.1 K with increasing pressure till ~ 28 GPa (P_c), at which point, with continued increasing pressure, there is a resurgence of the T_c until ~ 76 GPa (P_s), where the T_c now decreases slowly till ~ 141 GPa where the T_c is asymptotic until the maximum pressure measured of 171 GPa. While high-pressure XRD measurements confirmed a structural transition at P_s, no anomalies were detected in the M(T) at the P_c. To further investigate the nature of P_c, the dR(T)/dT was calculated from the R(T) data. The dR(T)/dT remains constant up to 7 T, suggesting the P_c is not magnetic and instead emerges from a Fermi surface topology change. Additional results from our investigation will also be presented, and possible further investigation routes will be discussed.