Superconductivity and Fermi Surface Nesting in the Candidate Dirac Semimetal NbC

TL;DR

This paper reports the synthesis and comprehensive characterization of NbC, revealing its dual nature as a conventional superconductor and a type-II Dirac semimetal with Fermi surface nesting, supported by experimental and theoretical evidence.

Contribution

It is the first to demonstrate that NbC is a type-II Dirac semimetal with strong Fermi surface nesting and unconventional superconducting behaviors.

Findings

NbC is a conventional superconductor with $T_c$ of 11.5 K.

NbC exhibits type-II Dirac semimetal properties with Fermi surface nesting.

Superconducting gaps show unconventional behaviors in ARPES measurements.

Abstract

We report the synthesis of single-crystal NbC, a transition metal carbide with various unusual properties. Transport, magnetic susceptibility, and specific heat measurements demonstrate that NbC is a conventional superconductor with a superconducting transition temperature ($T_c$) of 11.5 K. Our theoretical calculations show that NbC is a type-II Dirac semimetal with strong Fermi surface nesting, which is supported by our ARPES measurement results. We also observed the superconducting gaps of NbC using angle-resolved photoemission spectroscopy (ARPES) and found some unconventional behaviors. These intriguing superconducting and topological properties, combined with the high corrosion resistance, make NbC an ideal platform for both fundamental research and device applications.