van-der-Waals Compounds

Control of dimensionality in condensed matter continues to reveal novel quantum phenomena and effects. TMPX₃ (e.g. FePS₃) have proven to be ideal examples where structural, magnetic and electronic properties evolve into novel states when their dimensionality is tuned with pressure. At ambient pressure, they are two-dimensional van-der-Waals antiferromagnets, and Mott or charge-transfer insulators. Our recent studies[1-3] have reported dimensionality crossover related pressure-induced insulator-to-metal transitions and novel magnetic phases. There are also reports of superconductivity in a related member of this family of compounds. To further understand the structure and physical property evolution with pressure, we have performed a random structure search using first-principles calculations at high pressures and DFT+U studies to elucidate relationship between structural transitions, magnetism and electronic properties. Our computational explorations into pressure-tuned TMPX₃ are expected to guide the discovery of novel phases and superconductivity in these van-der-Waals systems.

[1] C. R. S. Haines, et al., Phys. Rev. Lett. 121, 266801 (2018).
[2] M. J. Coak, et al., J. Phys. Condens. Matter 32, 124003 (2020).
[3] M.J. Coak, et al., Phys. Rev. X, Oct (2020), Accepted