Half-metallic and ferromagnetic phases in CrSH monolayers using DFT+U and BO-MD calculations

We present a comprehensive investigation of the structural, electronic, magnetic, and vibrational properties of CrSH monolayers in the 1T and 1H phases using density functional theory (DFT)+U calculations with a converged Hubbard U value of 5.52 eV and Born-Oppenheimer molecular dynamics (BO-MD) simulations. The ferromagnetic (FM) 1T-CrSH phase is found to be dynamically and thermodynamically stable, exhibiting semiconducting behavior with a band gap of 1.1 eV and a magnetic moment of 3.0 μ_B per Cr atom. On the other hand, the 1H-CrSH phase is a half-metallic (HM) phase. We found that it is a metastable phase and undergoes a rapid phase transition to the 1T phase at a finite temperature at 300 K. Phonon calculations, performed using the finite displacement method and corrected for rotational invariance corrections with Huang and Born-Huang sum rules, resolve spurious imaginary frequencies in the flexural ZA phonon mode near the Γ-point, ensuring physical accuracy. These findings establish CrSH monolayers as promising candidates for spintronic and valleytronic applications, with tunable electronic properties enabled by phase engineering.