SKM 2021 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 1: Focus Session I: Ferroics - Domains and Domain Walls

KFM 1.5: Invited Talk

Tuesday, September 28, 2021, 11:30–12:00, H2

Magnetic avalanche of non-oxide conductive domain walls — Somnath Ghara¹, •Korbinian Geirhos¹, Lukas Kuerten², Peter Lunkenheimer¹, Vladimir Tsurkan¹, Manfred Fiebig², and István Kézsmárki¹ — ¹Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg, Germany — ²Department of Materials, ETH Zurich, 8093 Zurich, Switzerland

Conductive domain walls have been exclusively observed in oxides, where off-stoichiometry and defects often hamper the domain wall conductivity and render the walls immobile and thus curtail their usefulness and flexibility. In this talk, we will show the giant conductivity of domain walls in the non-oxide multiferroic GaV₄S₈, investigated by macroscopic transport as well as microscopic PFM and c-AFM measurements. We observe a fascinating architectures of ribbon- and folded sheet-like conductive domain walls emerging in the polar rhombohedral state below its Jahn-Teller transition T_JT = 45 K. Besides the giant negative magnetoresistance (∼80%) inherent to these conductive domain walls, their high conductivity is exploited to trigger unprecedentedly large changes of the bulk resistance via on-demand magnetic or electric conversions between multi- and mono-domain states. Such a transformation to the insulating mono-domain state through an avalanche-like domain-wall expulsion process leads to an abrupt conductance changes as large as eight orders of magnitude.

Reference: S. Ghara, K. Geirhos et al., Nature Communications 12, 3975 (2021).