Pressure-induced superconductivity in quasi-one-dimensional semimetal ${\mathrm{Ta}}_2{\mathrm{PdSe}}_6$

Abstract

Here we report the discovery of pressure-induced superconductivity in quasi-one-dimensional ${\mathrm{Ta}}_2{\mathrm{PdSe}}_6$, 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 $P_{\mathrm{c}}\sim 18.3$ GPa and is robust upon further compression up to $62.6$ GPa. The estimated upper critical field $\hat{I}{¼}_0{H}_{\mathrm{c}2}(0)$ in the pressurized ${\mathrm{Ta}}_2{\mathrm{PdSe}}_6$ is much lower than the Pauli limiting field, in contrast to the case in its isostructural analogs $M_2{\mathrm{Pd}}_{\mathrm{x}}{X}_5$ $(M=\mathrm{Nb}$, Ta; $X=\mathrm{S},\mathrm{Se})$. Concomitant with the occurrence of superconductivity, anomalies in pressuredependent 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 ${\mathrm{Ta}}_2{\mathrm{PdSe}}_6$.

7 pages, 7 figures