High-pressure transport and microcalorimetry studies on high qualityYbCu2Si2single crystals

Abstract

We report electrical transport and calorimetry studies on high quality single crystals of ${\text{YbCu}}_{2}{\text{Si}}_{2}$ under pressure in diamond and Bridgman anvil pressure cells with liquid pressure-transmitting media. At ambient pressure, in the best samples we find residual resistivities of less than $0.5\text{ }\ensuremath{\mu}\ensuremath{\Omega}\text{ }\text{cm}$. We have also determined the anisotropy of the temperature dependence of the resistivity and shown that this can account for sample-dependent differences of the resistivity. We confirm the previously reported transition to a magnetically ordered ground state with pressure and we have precisely determined the $(p,T)$ phase diagram using pure samples, good hydrostatic pressure conditions, and calorimetry measurements. Above 8.8 GPa we see a clear signature of the transition in the specific heat. We discuss the low-temperature resistivity and specific-heat behaviors in respect to the universal Kadowaki Woods ratio, to other ytterbium-based strongly correlated systems, and to the cerium-based counterpart, ${\text{CeCu}}_{2}{\text{Si}}_{2}$.