Pressure-Induced Charge-Order Melting and Reentrant Charge Carrier Localization in the Mixed-Valent Pb3Rh7O15

摘要

The mixed-valent Pb3Rh7O15 undergoes a Verwey-type transition at Tv ≈ 180 K,below which the development of Rh3+ /Rh4+ charge order induces an abrupt conductor-to-insulator transition in resistivity.Here we investigate the effect of pressure on the Verwey-type transition of Pb3Rh7O15 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 Pb3Rh7O15 undergo a reentrant localization under higher pressures.We have constructed a temperature-pressure phase diagram for Pb3Rh7 O15 and compared to that of Fe3 O4,showing an archetype Verwey transition.