Pressure-Induced Charge-Order Melting and Reentrant Charge Carrier Localization in the Mixed-Valent Pb3Rh7O15**Supported by the “Shi-Pei Ji Hua”, the National Science Foundation of China under Grant Nos 51402019 and 11574377, the Beijing Natural Science Foundation under Grant No 2152011, the National Basic Research Program of China under Grants No 2014CB921500, the Strategic Priority Research Program and Key Research Program of Frontier

Abstract

The mixed-valent PbRhO undergoes a Verwey-type transition at K, below which the development of Rh/Rh charge order induces an abrupt conductor-to-insulator transition in resistivity. Here we investigate the effect of pressure on the Verwey-type transition of PbRhO by measuring its electrical resistivity under hydrostatic pressures up to 8 GPa with a cubic anvil cell apparatus. We find that the application of high pressure can suppress the Verwey-type transition around 3 GPa, above which a metallic state is realized at temperatures below ∼70 K, suggesting the melting of charge order by pressure. Interestingly, the low-temperature metallic region shrinks gradually upon further increasing pressure and disappears completely at P > 7 GPa, which indicates that the charge carriers in PbRhO undergo a reentrant localization under higher pressures. We have constructed a temperature-pressure phase diagram for PbRhO and compared to that of FeO, showing an archetype Verwey transition.