Regensburg 2019 – wissenschaftliches Programm
MA 11.5: Hauptvortrag
Montag, 1. April 2019, 17:45–18:15, H38
Dissecting the magneto-structural transformation in materials with first-order field-induced transitions — •Konstantin Skokov — Technische Universität Darmstadt, 64287 Darmstadt, Germany
We report on a detailed study of the evolution occurring in the magnetic, electronic and structural subsystems of FeRh, La(FeSi)13, MnAs and Heuslers alloys, when the materials pass through a first-order field-induced transition. We have built a unique experimental setup which allows us to investigate the correlation between changes occurring in magnetization, magnetostriction, resistivity and the resulting magnetocaloric effect (MCE). The field-induced transitions from antiferromagnetic/paramagnetic to ferromagnetic states do not complete in one single step, as is commonly assumed. In fact, there are some well-distinguished and system dependent stages of the transition. In some stages the increase of magnetization and resulting MCE is the consequence of transformations taking place mainly in electronic subsystems containing carrying magnetic moment itinerant 3d electrons. In other stages the transformation in the electronic and magnetic subsystems is the result of lattice expansion/contraction. We demonstrate that it is possible to lock the sample in the intermediate state when the lattice parameters relate to the antiferromagnetic/paramagnetic state and the electronic structure and magnetization relate to the ferromagnetic state.
The work was supported by funding from the European Research Council (ERC), grant no. 743116 - project Cool Innov