Pressure-Induced Charge-Order Melting and Reentrant Charge Carrier Localization in the Mixed-Valent Pb$_{3}$Rh$_{7}$O$_{15}$
Yan Li1, Zhao Sun1, Jia-Wei Cai1, Jian-Ping Sun2,6, Bo-Sen Wang2,6, Zhi-Ying Zhao3,4, Y. Uwatoko5, Jia-Qiang Yan3, Jin-Guang Cheng2,6**
1College of Materials Science and Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617 2Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 3Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA 4Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA 5The Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan 6University of Chinese Academy of Sciences, Beijing 100049
Abstract：The mixed-valent Pb$_{3}$Rh$_{7}$O$_{15}$ undergoes a Verwey-type transition at $T_{\rm v} \approx 180$ K, below which the development of Rh$^{3+}$/Rh$^{4+}$ charge order induces an abrupt conductor-to-insulator transition in resistivity. Here we investigate the effect of pressure on the Verwey-type transition of Pb$_{3}$Rh$_{7}$O$_{15}$ 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 $\sim $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 Pb$_{3}$Rh$_{7}$O$_{15}$ undergo a reentrant localization under higher pressures. We have constructed a temperature-pressure phase diagram for Pb$_{3}$Rh$_{7}$O$_{15}$ and compared to that of Fe$_{3}$O$_{4}$, showing an archetype Verwey transition.
2017, Vol. 34 
