In this presentation, I will discuss our theoretical investigations into the electronic, magnetic, and dynamical properties of 4d transition-metal-based compounds, highlighting their potential as emerging topological quantum materials. We report the first prediction of non-trivial topological phases in yttrium iodide (YI), which hosts an unusual coexistence of spin-polarized Dirac and Weyl fermions within a single phase. Our calculations reveal twenty-five pairs of nodal points in the spin-up channel and six pairs in the spin-down channel. The Weyl nature of these nodes is confirmed through the identification of monopole-like source and sink features in the Berry curvature, along with the presence of topological Fermi arc states on the surface. These results establish YI as a type-II magnetic Weyl semimetal. Upon inclusion of spin–orbit coupling (SOC), eight pairs of Weyl nodes remain robust, while a small gap opens at the spin-polarized Dirac points. Notably, the system exhibits a high Dirac fermion velocity of approximately 3.4 × 105 m/s and a large, anisotropic intrinsic anomalous Hall conductivity reaching up to 933 S/cm. In addition, I will present our findings on zirconium nitride (ZrN) and a class of kagome lattice systems, which are predicted to host Dirac nodal line semimetal phases. The coexistence of Weyl and Dirac fermions, sizable anomalous Hall response, and widely separated Weyl nodes in momentum space highlight these materials as promising candidates for next-generation spintronic and quantum transport applications.

References:

[1] The Journal of Physical Chemistry C 129, 29, 13359-13365 (2025)
[2] Adv. Theory Simul.  7, 2300586 (2024)
[2] Adv. Theory Simul. 7,  2400298 (2024)