Monoclinic semimetal IrSi synthesized under high pressure above 25 GPa: Crystal structure, electronic, and magnetic properties

Transition metal monosilicides exhibit diverse physical properties depending on their crystal structures. Regarding IrSi, only the MnP-type orthorhombic form has been known so far. In this paper, the authors report a successful synthesis of a monoclinic phase through high-pressure high-temperature treatment above 25 GPa, while the theoretically predicted B20-type cubic structure has not been identified up to 48 GPa. Magneto-transport measurements reveal a semimetallic nature of the monoclinic form with a low carrier density of ~1019 /cm${}^{3}$. Combined with large Rashba spin splitting of surface electronic bands, monoclinic IrSi may offer a potential material platform for versatile spintronic applications in the two-dimensional limit.