Ab initio dynamical mean field theory study on the electronic structure and magnetism of Fe_1/3NbS₂

Materials with magnetic ions intercalated between layers of transition-metal dichalcogenide (TMD) host a wide range of interesting electrical and magnetic properties[1,2]. Recent DFT studies[3,4] on the iron intercalated NbS₂ have provided only partial insights into the relative stability of two competing magnetic phases around the critical doping ratio 1/3 of the Fe ions, while failed to explain the sensitive changes of experimental ARPES spectra around this ratio[4]. In addition, DFT+U calculations underestimate the experimentally determined local magnetic moments[3,4]. In this study, we show that ab initio DMFT with coupled cluster impurity solver[5,6] is able to predict a magnetic moment that closely matches the experimental one, and explain the evolution of flat bands as a function of the doping ratio around 1/3. We also investigate the origin of the critical doping ratio 1/3 for electrical and magnetic properties in this material. Several technical improvements which make these studies feasible, such as an ab initio multi-impurity formulation of DMFT and supercell band unfolding[7], will also be discussed.

[1] Nair, et al., Nat. Mater. 19, 153 (2019).

[2] Wu, et al., Phys. Rev. X 12, 021003 (2022)

[3] Weber, Neaton, Phys. Rev. B 103, 214439 (2021)

[4] Li, et al., arXiv:2509.03327

[5] Zhu, et al., Phys. Rev. B 100, 115154 (2019)

[6] Zhu, Cui, Chan, J. Chem. Theory Comput. 16, 01141-153 (2020)

[7] Ku, Berlijin, Lee, Phys. Rev. Lett. 104, 216401 (2010)