Regensburg 2019 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 7: Multiferroics
KFM 7.5: Talk
Monday, April 1, 2019, 16:20–16:40, H47
Orbital-Order Driven Ferroelectricity and Dipolar Relaxation Dynamics in Multiferroic GaMo4S8 — •Korbinian Geirhos1, Peter Lunkenheimer1, Hiroyuki Nakamura2, Takeshi Waki2, Yoshikazu Tabata2, and Istvan Kezsmarki1 — 1Experimental Physics V, EKM, University of Augsburg — 2Department of Materials Science and Engineering, Kyoto University, Japan
GaMo4S8, a compound of the lacunar spinel family, was recently shown to exhibit non-canonical, orbitally-driven ferroelectricity [1]. Our dielectric spectroscopy measurements on this multiferroic material reveal complex relaxation dynamics, above as well as below its Jahn-Teller transition at TJT = 47 K [2]. Above the Jahn-Teller transition, two types of coupled dipolar-orbital dynamics were found: On the one hand, relaxations within cluster-like regions with short-range polar order, as known from relaxor ferroelectrics. On the other hand, critical fluctuations of only weakly interacting dipoles, resembling the typical dynamics of order-disorder type ferroelectrics. Below TJT, the system is driven into long range ferrolectric order by the onset of orbital order and dipolar dynamics within the ferroelectric domains is observed: The found marked differences to the skyrmion host GaV4S8, seem to be related to the different structural distortions in these systems.
[1] E. Neuber,et al., J. Phys.: Condens. Matter 30, 445402 (2018) [2] K. Geirhos, et al., arXiv:1810.07145