Superconductivity in hard nitride cP6-WN

The search for novel nitride superconductors with superior mechanical properties is highly demanded for many potential applications, which, however, have been scarcely succeeded for the late 5d transition-metal nitrides, especially for the binary W-N compounds. Here we report the experimental identification of superconductivity in cubic cP6-WN with the NbO-type structure by electrical transport, magnetization, and specific heat measurements, based on high-pressure synthesized samples. The superconducting properties of cP6-WN are well determined and it belongs to a bulk type-II superconductor with a critical onset temperature of Tc=2.86K, showing weak electron-phonon coupling, short coherence length, and high upper critical field, likely due to its unique electronic and structural features. Pressure may slightly enhance electron-phonon interactions for gently promoting its Tc up to 3.83 K at 81 GPa, indicating the remarkable robustness of its superconductivity to external stress. This, combined with its exceptional mechanical hardness that rivals that of tungsten carbide (WC), makes it a compelling candidate for fabrication of durable superconducting electronics and coatings operating under high-stress conditions.