Regensburg 2019 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 7: Multiferroics
KFM 7.7: Vortrag
Montag, 1. April 2019, 17:30–17:50, H47
Imaging of ferroelectric domains in Ca3Mn1.9Ti0.1O7 by second harmonic generation — •Yannik Zemp1, Mads C. Weber1, Thomas Lottermoser1, Bin Gao2, Sang-Wook Cheong2, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich — 2Rutgers University, New Jersey
One of the most important challenges towards the application of multiferroics – materials with coexisting magnetic and ferroelectric order, is to find a material with a robust coupling between ferroelectricity and magnetism and a sufficiently large polarisation at high temperatures. Magnetic hybrid-improper ferroelectrics, in particular Ca3Mn2O7, where magnetism and ferroelectricity are induced through the same lattice instability, were theoretically proposed as a possible solution. Experimentally, however, ferroelectric switching at room temperature has still not been achieved. Already an important hallmark for ferroelectricity would be the observation of polar domains. Here, we investigate Ti-stabilised Ca3Mn2O7 by optical second harmonic generation imaging – a method that is highly sensitive to a breaking of inversion symmetry and hence the ideal non-destructive tool to probe for ferroelectricity. We show the existence of polar domains, oriented 90∘ towards each other, at room temperature and additional 180∘ domains within them. This domain structure can be directly linked to the complex structural distortion mechanism and gives rise to a rich domain wall structure. These findings are an important milestone towards the detection of multiferroicity and magnetoelectric coupling in Ca3Mn2O7.