Pressure-induced metallization of BaMn2As2

Abstract

Temperature- and pressure-dependent electrical resistivity [($\ensuremath{\rho}T$,$P$)] studies have been performed on BaMn${}_{2}$As${}_{2}$ single crystal in the 4.2--300 K range up to 8.2 GPa in order to investigate the evolution of its ground state properties. \ensuremath{\rho}($T$) data show negative coefficients of resistivity up to a pressure of 3.2 GPa. At a pressure of \ensuremath{\sim}4.5 GPa an insulator-to-metal transition is seen to occur at \ensuremath{\sim}36 K, as indicated by a change in the temperature coefficient of the \ensuremath{\rho}($T$). However, at a pressure of \ensuremath{\sim}5.8 GPa the sample is metallic in the entire temperature range. X-ray diffraction studies performed as a function of pressure, at room temperature, also show an anomaly in the pressure versus volume curve around $P$ \ensuremath{\approx} 5 GPa without a change in crystal structure, indicative of an electronic transition in support of the resistivity results. In addition to metallization, a clear precipitous drop in \ensuremath{\rho}($T$) is seen at \ensuremath{\sim}17 K for $P$ \ensuremath{\ge} 5.8 GPa.