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.