NbSeTe—a new layered transition metal dichalcogenide superconductor

Transition metal dichalcogenides (TMDCs) usually exhibit layered polytypic structures due to the weak interlayer coupling. 2H-NbSe 2 is one of the most widely studied in the pristine TMDC family due to its high superconducting transition temperature ( T c = 7.3 K) 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-NbSe 2 by 3 d transition metals without significantly changing its crystal structure. Here we replaced the Se by Te in 2H-NbSe 2 in order to design a new 1T polytype layered TMDC NbSeTe, which adopts a trigonal structure with space group P m 1. We successfully grew large size and high-quality single crystals of 1T-NbSeTe via the vapor transport method using I 2 as the transport agent. Temperature-dependent resistivity and specific heat data revealed a bulk T c 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.