Emergent Magnetic Phases in Pressure-Tuned van der Waals Antiferromagnet FePS3

• Published in: Physical review. X Vol. 11; no. 1
• Main Authors: Coak, Matthew J, Jarvis, David M, Hamidov, Hayrullo, Wildes, Andrew R, Paddison, Joseph A M, Liu, Cheng, Haines, Charles R S, Dang, Ngoc T, Kichanov, Sergey E, Savenko, Boris N, Lee, Sungmin, Kratochvílová, Marie, Klotz, Stefan, Hansen, Thomas C, Kozlenko, Denis P, Park, Je-Geun, Saxena, Siddharth S
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 05.02.2021
• Subjects: Antiferromagnetism; Circuits; Condensed matter physics; Ferromagnetism; Graphene; Long range order; Magnetic materials; Magnetic measurement; Magnetic properties; Magnetic structure; Magnetism; Neutron diffraction; Physics; Room temperature; Short range order; Spintronics; Superconductivity; Switches; Unit cell
• ISSN: 2160-3308
• DOI: 10.1103/PhysRevX.11.011024

Layered van der Waals 2D magnetic materials are of great interest in fundamental condensed-matter physics research, as well as for potential applications in spintronics and device physics. We present neutron powder diffraction data using new ultrahigh-pressure techniques to measure the magnetic structure of Mott-insulating 2D honeycomb antiferromagnetFePS3at pressures up to 183 kbar and temperatures down to 80 K. These data are complemented by high-pressure magnetometry and reverse Monte Carlo modeling of the spin configurations. As pressure is applied, the previously measured ambient-pressure magnetic order switches from an antiferromagnetic to a ferromagnetic interplanar interaction and from 2D-like to 3D-like character. The overall antiferromagnetic structure within theabplanes, ferromagnetic chains antiferromagnetically coupled, is preserved, but the magnetic propagation vector is altered fromk=(0,1,12)tok=(0,1,0), a halving of the magnetic unit cell size. At higher pressures, coincident with the second structural transition and the insulator-metal transition in this compound, we observe a suppression of this long-range order and emergence of a form of magnetic short-range order which survives above room temperature. Reverse Monte Carlo fitting suggests this phase to be a short-ranged version of the original ambient-pressure structure—with the Fe moment size remaining of similar magnitude and with a return to antiferromagnetic interplanar correlations. The persistence of magnetism well into the HP-II metallic state is an observation in contradiction with previous x-ray spectroscopy results which suggest a spin-crossover transition.