IrSi as a Superior Electronic Material with Novel Topological Properties and Nice Compatibility with Semiconductor Si

To favor the applications in electronic devices, topological semimetals require not only excellent topological electronic structures but also nice compatibility with the traditional Si-based semiconductor. Herein, IrSi compound is revealed as a superior electronic material which satisfies both criteria proposed earlier. First, IrSi hosts novel band topology with multiple fermionic states. Without spin-orbit coupling (SOC), IrSi shows an accidental node loop, protected by two independent mechanisms. With SOC included, it shows two symmetry-enforced nodal lines (NLs) and Dirac points (DPs). The presence of NLs and DPs under SOC has been verified by symmetry analysis. Remarkably, the DPs in IrSi locate quite near the Fermi level and possess type-II band dispersions, which are rarely identified in Dirac semimetals. Second, IrSi has already been prepared on epitaxial Si wafers and thereby has been fabricated as IrSi/Si devices with excellent compatibility in previous experiments. This work further shows that the nodal loop and DPs are robust against potential lattice distortion during its epitaxial growth.