Pressure-induced superconductivity in quasi-one-dimensional semimetal Ta2PdSe6

Here we report the discovery of pressure-induced superconductivity in quasi-one-dimensional Ta2PdSe6, through a combination of electrical transport, synchrotron x-ray diffraction, and theoretical calculations. Our transport measurements show that the superconductivity appears at a critical pressure P-c similar to 18.3 GPa and is robust upon further compression up to 62.6 GPa. The estimated upper critical field mu H-0(c2)(0) in the pressurized Ta2PdSe6 is much lower than the Pauli limiting field, in contrast to the case in its isostructural analogs M2PdxX5 (M = Nb, Ta; X = S, Se). Concomitant with the occurrence of superconductivity, anomalies in pressure-dependent transport properties are observed, including sign reversal of Hall coefficient, abnormally enhanced resistance, and dramatically suppressed magnetoresistance. Meanwhile, room-temperature synchrotron x-ray diffraction experiments reveal the stability of the pristine monoclinic structure (space group C2/m) upon compression. Combined with the density functional theory calculations, we argue that a pressure-induced Lifshitz transition could be the electronic origin of the emergent superconductivity in Ta2PdSc6.

Automated summary

In this study, we report the discovery of pressure-induced superconductivity in quasi-one-dimensional compound Ta2PdSe6 through a combination of electrical transport, synchrotron x-ray diffraction, and theoretical calculations. The superconductivity in Ta2PdSe6 appears at a critical pressure of around 18.3 GPa and remains stable up to 62.6 GPa. Anomalies in pressure-dependent transport properties, such as sign reversal of Hall coefficient, enhanced resistance, and suppressed magnetoresistance, are observed concomitant with the occurrence of superconductivity. Synchrotron x-ray diffraction experiments confirm the stability of the structure upon compression, and density functional theory calculations suggest that a pressure-induced Lifshitz transition could be the electronic origin of the emergent superconductivity in Ta2PdSe6.