Dresden 2020 – wissenschaftliches Programm
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KFM 4.3: Vortrag
Montag, 16. März 2020, 15:40–16:00, HSZ 105
Investigation of multiferroic coupling in Ca3Mn1.9Ti0.1O7 by optical second harmonic generation — •Yannik Zemp1, Mads Weber1, Thomas Lottermoser1, Morgan Trassin1, Bin Gao2, Sang-Wook Cheong2, and Manfred Fiebig1 — 1Department of Materials, ETH Zurich — 2Rutgers University, New Jersey
Layered perovskite materials, such as A3B2O7 Ruddlesden-Popper compounds, are under scrutiny in the search for multiferroics with a strong magnetoelectric coupling and large polarisations at high temperatures. Their crystal structure allows for the implementation of a wide range of magnetic ions and it can be host to geometrically induced ferroelectricity. For Ca3Mn2O7, theory predicts a robust magnetoelectric coupling between the improper ferroelectricity and the Mn3+ magnetism, mediated by the MnO6-octahedra tilts. However, experimental evidence is still pending. Here, we investigate such a possible coupling in Ca3Mn1.9Ti0.1O7. We probe the influence of the magnetic ordering on the ferroelectricity using second harmonic generation (SHG) - a non-invasive, highly symmetry-sensitive laseroptical technique ideal for the study of ferroic order. We observe a strong increase in the SHG signal upon entering the magnetic phase, which indicates a strong influence of the magnetism on the ferroelectricity. Measurements of the SHG spectrum and images of the domain pattern suggest a coupling of the magnetic order to the polarisation mechanism via the octahedral tilts. Our results demonstrate that layered perovskites are promising candidates in search for multiferroics with pronounced magnetoelectric coupling.