Abstract
Previous works have controversially claimed near-room-temperature ferromagnetism in two-dimensional (2D) VSe2, with conflicting results throughout the literature. These discrepancies in magnetic properties between both phases (T and H) of 2D VSe2 are most likely due to the structural parameters being coupled to the magnetic properties. Specifically, both phases have a close lattice match and similar total energies, which makes it difficult to determine which phase is being observed experimentally. In this study, we used a combination of density functional theory, highly accurate diffusion Monte Carlo (DMC), and a surrogate Hessian line-search optimization technique to resolve the previously reported discrepancy in structural parameters and relative phase stability. With DMC accuracy, we determined the free-standing geometry of both phases and constructed a phase diagram. Our findings demonstrate the successes of the DMC method coupled with the surrogate Hessian structural optimization technique when applied to a 2D magnetic system.
| Original language | English |
|---|---|
| Pages (from-to) | 3553-3560 |
| Number of pages | 8 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 14 |
| Issue number | 14 |
| DOIs | |
| State | Published - Apr 13 2023 |
Funding
This work was supported by the National Science Foundation through the Division of Materials Research under NSF Grant No. DMR-2213398. The authors thank the National Institute of Standards and Technology for funding, computational, and data-management resources. Work by J.T and J.T.K. (stochastic structure optimization, writing) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as part of the Computational Materials Sciences Program and Center for Predictive Simulation of Functional Materials. Work by K.S. conceptual idea and writing) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. We acknowledge grants of computer capacity from the Finnish Grid and Cloud Infrastructure (persistent identifier urn:nbn:fi:research-infras-2016072533). The authors thank Dr. Kamal Choudhary and Dr. Francesca Tavazza for fruitful discussions.