Dresden 2017 – scientific programme

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DF: Fachverband Dielektrische Festkörper

DF 17: Ferroics - Domains, Domain Walls and Skyrmions IV

DF 17.5: Talk

Thursday, March 23, 2017, 11:00–11:15, WIL B321

Probing ferroelectricity in multiferroic Dy_0.7Tb_0.3FeO₃ using second harmonic generation — •Ehsan Hassanpour Yesaghi¹, Yusuke Tokunaga², Thomas Lottermoser¹, Yasujiro Taguchi³, and Yoshinori Tokura^3,4 — ¹Department of Materials, ETH Zürich, Zürich, Switzerland — ²Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba 277-8561, Japan — ³RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198, Japan — ⁴Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), University of Tokyo, Tokyo 113-8656, Japan

Multiferroic Dy_0.7Tb_0.3FeO₃ is reported to host a magnetically-driven spontaneous polarization below 2.65 K. This polarization emerges as a result of exchange interaction between Fe³⁺ spins and rare-earth moments. At about 2 K the polarization vanishes due to the change in the magnetic phase of iron (ferromagnetic to antiferromagnetic). Some models have been proposed on the magnetoelectric coupling in this material but a profound experimental study is yet to be done. Here we investigate the magnetic and electric order at the level of domains using spatially resolved techniques. We employ optical Faraday effect and second harmonic generation (SHG) to investigate the magnetic and electric order respectively. Our results reveal that the transition at 2 K is not sharp and the two types of ordering for the Fe³⁺ spins coexist simultaneously from which only one (ferromagnetic phase) contributes to the spontaneous polarization. The volume ratio of these two phases, and hence the amplitude of the ferroelectric polarization, can be controlled via an external magnetic field.