Magnetic and Spin-Orbit Coupling Effects in LiGaX₂ (X = S, Se, Te): Insights from First-Principles DFT Studies

Abstract

CONTEXT

This study investigates the magnetic properties and spin-orbit coupling (SOC) effects in ternary tetragonal LiGaX₂ (X = S, Se, Te) compounds, motivated by their potential applications in spintronics and quantum materials. The pristine compounds exhibit a non-magnetic ground state due to fully paired valence electrons, as confirmed by spin-polarized density functional theory (DFT) calculations. However, introducing defects, vacancies, or transition metal dopants can induce magnetism through the emergence of unpaired electrons or partially filled d-orbitals. Computed magnetic moments for LiGaS₂, LiGaSe₂, and LiGaTe₂ are minimal, with values of 0.00219 μB, -0.00242 μB, and -0.00141 μB, respectively, while interstitial magnetic moments range from 0.00033 μB to 0.00433 μB. SOC effects, particularly significant in LiGaTe₂ due to strong Te 5p orbital interactions, lead to band splitting, reduced band gaps, and altered magnetic anisotropy.

METHODS

First-principles calculations were carried out using density functional theory (DFT) within the generalized gradient approximation (GGA). Spin-polarized calculations and SOC effects were included to analyze magnetic properties and electronic structure. All computations were performed using the WIEN2k code based on the full-potential linearized augmented plane wave (FP-LAPW) method. Structural optimization and total energy calculations were conducted to determine the ground-state properties of the LiGaX₂ compounds.