Magnetic properties of epitaxial $\beta $-Nb2N thin film on SiC substrate

Previously superconductivity in Nb$_{\mathrm{2}}$N was studied in thin films synthesized by reactive magnetron sputtering or pulsed laser deposition.[1][2] Recently, Nb$_{\mathrm{2}}$N was synthesized by molecular beam epitaxy (MBE).[3] Here, we report on the magnetic properties of MBE grown Nb$_{\mathrm{2}}$N measured by SQUID magnetometry. The single hexagonal $\beta $ phase Nb$_{\mathrm{2}}$N is grown on a semi-insulating Si-face 4H SiC (0001) substrate in nitrogen rich conditions at a substrate temperature of 850 ${^\circ}$C.[3] In-plane magnetization as a function of magnetic field measured at 5 K shows type-II superconductivity with critical fields H$_{\mathrm{c1}}$ and H$_{\mathrm{c2}}$ of 300 Oe and 10 kOe, respectively. In-plane field-cooled and zero-field-cooled a critical temperature (T$_{\mathrm{c}})$ of 11.5 K, higher than in sputtered Nb$_{\mathrm{2}}$N films. This work was supported by Army Research Office and the Office of Naval Research. [1] Treece et. al. Chem. Mater. 6, 2205 (1994) [2] Chockalingam et. al. PRB 77, 214503 (2008) [3] Katzer et. al. APEX 8, 085501 (2015)