High Pressure Superconductivity and Amorphization in Iron Chalcogen Fe(Se$_{0.5}$Te$_{0.5})$ to 70 GPa

Superconductivity and structural phase transitions in Iron-based layered superconductor Fe(Se$_{0.5}$Te$_{0.5})$ has been studied to high pressures of 70 GPa and temperature of 10 K using designer diamond anvils and x-ray diffraction using a synchrotron source. Four probe electrical resistance measurements show onset of superconductivity (T$_{c})$ at 14 K at ambient pressure with T$_{c}$ increasing with increasing pressure to 19 K at a pressure of 3.6 GPa. At higher pressures beyond 3.6 GPa, T$_{c}$ decreases and extrapolation suggests non superconducting behavior above 10 GPa. X-ray diffraction studies at room temperature show transformation from ambient pressure tetragonal phase to an amorphous phase above 11 GPa and the amorphous phase remains stable till the highest pressure of 70 GPa. The amorphous phase is observed to revert back to the parent tetragonal PbO structure upon decreasing pressure.