Berlin 2012 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 8: Multiferroics III (jointly with MA, DS, KR, TT)

DF 8.2: Vortrag

Dienstag, 27. März 2012, 09:45–10:00, EB 301

Directly probing the effect of strain on magnetic exchange interactions — •Kathrin Dörr^1,2, Andreas Herklotz², Hans-Martin Christen³, and Michael Biegalski³ — ¹MLU Halle Wittenberg, Von-Danckelmann-Platz 3, 06120 Halle — ²IFW Dresden, Postfach 270116, 01171 Dresden — ³CNMS, Oak Ridge National Laboratory, Oak Ridge, TN 37830, USA

Thin films of transition metal oxides of the perovskite type ABO₃ (B = 3d or 4d metal) have revealed abundant examples for strain-driven changes of magnetic ordering. In spite of strong efforts, the theoretical treatment of magnetic exchange in complex oxides has remained a challenge, and experiments continue to show unpredicted large effects of the epitaxial strains in films. In order to provide meaningful experimental data on strain dependences, epitaxial thin films should be grown in various coherent strain states on different substrates without changing anything but the strain. This is inherently difficult: possible problems arise from a strain-dependent oxidation level or microstructure. As a complementary approach, the in-plane strain of epitaxial oxide films can be controlled reversibly by 0.1-0.2 percent using a piezoelectric substrate. I will address reversible-strain studies on La_0.7Sr_0.3MnO₃, La_1−xSr_xCoO₃ (x = 0, 0.2, 0.3) und SrRuO₃ films, showing the strain response of the magnetic Curie temperature and the magnetization and discussing the current understanding of the strain effects on magnetic ordering.