Electronic structure of αRuCl3 by fixed-node and fixed-phase diffusion Monte Carlo methods

Abdulgani Annaberdiyev, Cody A. Melton, Guangming Wang, and Lubos Mitas
Phys. Rev. B 106, 075127 – Published 15 August 2022
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Abstract

Layered material αRuCl3 has caught wide attention due to its possible realization of Kitaev's spin liquid and its electronic structure that involves the interplay of electron-electron correlations and spin-orbit effects. Several DFT+U studies have suggested that both electron-electron correlations and spin-orbit effects are crucial for accurately describing the band gap. This work studies the importance of these two effects using fixed-node and fixed-phase diffusion Monte Carlo calculations both in spin-averaged and explicit spin-orbit formalisms. In the latter, the Slater-Jastrow trial function is constructed from two-component spin orbitals using our recent quantum Monte Carlo (QMC) developments and thoroughly tested effective core potentials. Our results show that the gap in the ideal crystal is already accurately described by the spin-averaged case, with the dominant role being played by the magnetic ground state with significant exchange and electron correlation effects. We find qualitative agreement between hybrid DFT, DFT+U, and QMC. In addition, QMC results agree very well with available experiments, and we identify the values of exact Fock exchange mixing that provide comparable gaps. Explicit spin-orbit QMC calculations reveal that the effect of spin-orbit coupling on the gap is minor, of the order of 0.2 eV, which corresponds to the strength of the spin orbit of the Ru atom.

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  • Received 29 March 2022
  • Revised 17 June 2022
  • Accepted 3 August 2022

DOI:https://doi.org/10.1103/PhysRevB.106.075127

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Abdulgani Annaberdiyev1,2, Cody A. Melton3, Guangming Wang1, and Lubos Mitas1

  • 1Department of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
  • 2Center for Nanophase Materials Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  • 3Sandia National Laboratories, Albuquerque, New Mexico 87123, USA

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Issue

Vol. 106, Iss. 7 — 15 August 2022

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