NbSeTe -A New Layered Transition Metal Dichalcogenide Superconductor

TL;DR

This paper reports the discovery of superconductivity in a new layered transition metal dichalcogenide, 1T-NbSeTe, with a trigonal structure, expanding the family of TMDC superconductors and enabling studies of charge-density wave interactions.

Contribution

It introduces a new 1T polytype TMDC, NbSeTe, with high-quality single crystals and demonstrates its superconductivity at 1.3 K, which was not previously observed in this phase.

Findings

Superconductivity observed at 1.3 K in 1T-NbSeTe

Successful growth of high-quality single crystals

Enlarges the family of superconducting TMDCs

Abstract

Transition metal dichalcogenides (TMDCs) usually exhibit layered polytypic structures due to the weak interlayer coupling. 2H-NbSe2 is one of the most widely studied in the pristine TMDC family due to its high superconducting transition temperature (Tc = 7.3K) and the occurrence of a charge-density wave (CDW) order below 33 K. The coexistence of CDW with superconductivity poses an intriguing open question about the relationship between Fermi surface nesting and Cooper pairing. Past studies of this issue have mostly been focused on doping 2H-NbSe2 by 3d transition metals without significantly changing its crystal structure. Here we replaced the Se by Te in 2H-NbSe2 in order to design a new 1T polytype layered TMDC NbSeTe, which adopts a trigonal structure with space group P-3m1. We successfully grew large size and high-quality single crystals of 1T-NbSeTe via the vapor transport method using I2 as the transport agent. Temperature-dependent resistivity and specific heat data revealed a bulk Tc at 1.3 K, which is the first observation of superconductivity in pure 1T-NbSeTe phase. This compound enlarged the family of superconducting TMDCs and provides an opportunity to study the interplay between CDW and superconductivity in the trigonal structure.