Pressure-induced semiconductor-semimetal transition in Rb$_{0.8}$Fe$_{1.6}$S$_2$

The transport and magnetic properties of the Rb$_{0.8}$Fe$_{1.6}$S$_2$ crystal have been studied under quasihydrostatic compression to a pressure of 40.5 GPa in diamond anvil cells. A semiconductor-semimetal electronic transition has been detected at a pressure of about 15 GPa. In addition, the disappearance of the magnetic order down to a temperature of 3 K has been found at a pressure of 24 GPa. It has been shown that, in contrast to a similar selenium compound Rb$_{0.8}$Fe$_{1.6}$S$_2$, superconductivity in Rb$_{0.8}$Fe$_{1.6}$S$_2$ sulfide does not appear down to the lowest temperatures even at an external pressure of 40.5 GPa.