SKM 2023 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MA: Fachverband Magnetismus

MA 46: Ultrafast Magnetization Effects II

MA 46.5: Vortrag

Freitag, 31. März 2023, 10:30–10:45, HSZ 02

Dynamics of the Morin transition in hematite — •Maik Kerstingskötter¹, Tobias Dannegger¹, András Deák², László Szunyogh^2,3, and Ulrich Nowak¹ — ¹Department of Physics, University of Konstanz — ²Department of Theoretical Physics, Budapest University of Technology and Economics — ³ELKH-BME Condensed Matter Research Group, Budapest University of Technology and Economics

Below a critical temperature T_M of about 264 K, hematite is a perfect antiferromagnet with zero net magnetization due to the fact that the spins of the four sublattices are antiparallel and aligned with the c-axis. If the temperature exceeds this critical point, the spins reorient into the basal plane and assume a small canting angle that results in a finite net magnetization. This first-order phase transition from the antiferromagnet to the weak ferromagnetic phase is the Morin transition. While the equilibrium properties are well known, we want to investigate the nonequilibrium dynamics of the transition. Here we use atomistic spin dynamics simulations on the basis of an ab initio model to study the system’s response to an instantaneous temperature increase from T<T_M to T>T_M. In the model used, we indeed observe this Morin transition, which takes place in the range of five to a few hundred picoseconds, depending on the size of the Gilbert damping used.