Speaker
Description
Control of dimensionality in condensed matter continues to reveal novel quantum phenomena and effects. Transition metal phosphorous trichalcogenides TM P X 3 (TM = Mn, Fe, Ni, V, etc., X = S, Se) 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 with strongly correlated physics. Our recent experimental studies [1-4] have shown dimensionality crossover related pressure-induced insulator-to-metal transitions and novel magnetic phases in FePS3. To elucidate the relationship between structural transitions, magnetism and electronic properties, we also performed a random structure search using first-principles calculations at high pressures and DFT+U studies [5]. We experimentally explored the coexistence of the low- and intermediate-pressure phases, and we predict a novel high-pressure phase with distinctive dimensionality and possible options for interpreting the origins of metallicity.
We will also present our most recent single-crystal high-pressure synchrotron X-ray study on crystalline structures and the high-pressure neutron scattering study on magnetic structures of FePSe3, a similar compound to FePS3 with reported high-pressure induced superconductivity occurring at 2.5 K and 9.0 GPa [6]. The new work performed at the DIAMOND light source and Institut Laue Langevin finally provides clear crystallographic assignments related to phases which emerge with the application of pressure.
References:
[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, 11, 011024 (2021).
[4] D. M. Jarvis, et al., Phys. Rev. B, 107, 54106 (2023).
[5] S. Deng, et al., SciPost Phys. 15, 020 (2023).
[6] Y. Wang, et al., Nat. Commun. 9, 1914 (2018).
