OxTalks will soon be transitioning to Oxford Events (full details are available on the Staff Gateway). A two-week publishing freeze is expected in early Hilary to allow all events to be migrated to the new platform. During this period, you will not be able to submit or edit events on OxTalks. The exact freeze dates will be confirmed as soon as possible.
If you have any questions, please contact halo@digital.ox.ac.uk
First-order (discontinuous) phase transitions between magnetic states can provide huge entropy and temperature changes driven by the application of small external stimuli, the so-called caloric effect exploited in the design of cooling cycles [1]. We present an approach based on density functional theory (DFT) calculations of magnetically constrained supercells to compute the magnetic Gibbs free energy of materials [2,3]. The minimization of this free energy predicts and explains the character of phase transitions at finite temperature in terms of both purely electronic and magnetoelastic mechanisms, the former arising from the presence of multisite magnetic interactions [4]. The performance of two different DFT codes, the Vienna Ab Initio Simulation package (VASP) and the linear-scaling KKR-nano suitable for thousands of atoms (jukkr.fz-juelich.de), will be demonstrated. Results obtained for some materials, including the triangular antiferromagnetic state in antiperovskite systems, will be shown and compared with experiment.
[1] X. Moya et al., Nature Materials 13, 439 (2014).
[2] B.L. Gyorffy et al., J. Phys. F: 15, 1337 (1985).
[3] E. Mendive-Tapia, J. Neugebauer, and T. Hickel, Phys. Rev. B 105, 064425 (2022).
[4] E. Mendive-Tapia and J.B. Staunton, Phys. Rev. B 99, 144424 (2019).
