Pressure-induced superconductivity at 32 K in MoB 2 .

Since the discovery of superconductivity in MgB 2 ( T c ∼ 39 K), the search for superconductivity in related materials with similar structures or ingredients has never stopped. Although about 100 binary borides have been explored, only a few of them show superconductivity with relatively low T c . In this work, we report the discovery of superconductivity up to 32 K, which is the highest T c in transition-metal borides, in MoB 2 under pressure. The T c of MoB 2 in the α phase can be well explained by theoretical calculations in the framework of electron-phonon coupling. Furthermore, the coupling between the d electrons of Mo and the out-of-plane Mo-phonon modes are the main driving force of the 32 K superconductivity of MoB 2 . Our study sheds light on the exploration of high- T c superconductors in transition metal borides.