Emergent superconductivity from suppression of charge order in pressurized Re3Ge7

Abstract

The emergence of superconductivity is often accompanied by competing charge/magnetic orders, such as charge/spin density waves and antiferromagnetism in correlated systems. The superconducting temperature TC can often be significantly enhanced once the competing order is suppressed via external stimuli. Recently, Re3Ge7 has attracted considerable attention due to its temperature-induced metal-insulator-like transition, which is inexplicably related to superconductivity. In this study, we have discovered that Re3Ge7 single crystals exhibit pressure-induced superconductivity due to the suppression of charge order. Re3Ge7 displays an insulatorlike upturn of electronic resistivity bellow 60 K at ambient pressure without triggering a structure transition. The dominant carrier changes from electrons to holes at low temperatures. The temperature-dependent angle-resolved photoemission spectroscopy investigations indicated that the band structure of Re3Ge7 does not appear to alter significantly between 70 K and 7 K. After ruling out some possible competing orders based on experimental evidence, we suggest that the insulatorlike state could be the unconventional charge ordering's plausible ground state. Our findings indicate that the emergence of superconductivity can be achieved at a relatively low pressure of 0.2 GPa by restraining the charge order. With increasing pressure, TC is slightly enhanced, reaching a maximum value of 5.3 K at 24.1 GPa, while the charge order is rapidly inhibited until it becomes imperceptible. The superconductivity shows an unusual platform-shaped phase diagram, suggesting the possibility of unconventional electronic contributions. The current research poses important questions concerning the Re3Ge7 unconventional charge order and how it competes with the appearance of superconductivity.

Source-reported materials — not catalogue approval

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