Berlin 2012 – scientific programme
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DS: Fachverband Dünne Schichten
DS 17: Multiferroics III: Strain / New routes towards multiferroicity (jointly with MA, DF, KR, TT)
DS 17.4: Talk
Tuesday, March 27, 2012, 10:15–10:30, EB 301
Search for strain-induced ferroelectricity in EuO films — •Carsten Becher1, Masakazu Matsubara1, Andreas Schmehl2, Jochen Mannhart3, Darrell G. Schlom4, and Manfred Fiebig1 — 1Department of Materials, ETH Zürich, Switzerland — 2Institut für Physik, Universität Augsburg, Germany — 3Max Planck Institute for Solid State Research, Germany — 4Department of Materials Science and Engineering, Cornell University, USA
Ferromagnetic EuO arouses a lot of interest due to a multitude of extreme properties, such as an insulator-metal transition, a colossal-exceptional magnetoresistance effect, and nearly 100 % spin polarization of the conduction electrons in the ferromagnetic state. In addition, recent theories predict that EuO becomes ferroelectric under epitaxial strains ≥ 4.2 %, suggesting a route to novel multiferroics combining ferromagnetic and ferroelectric order. Here, we use optical second harmonic generation (SHG) to detect changes of the electric as well as magnetic order of EuO thin films. In search of a strain-induced spontaneous polarization, we vary the sample temperature, apply electric and magnetic fields in various configurations, and use different photon energies of the incident laser pulses. So far, we verified that samples strained below 4 % do not display ferroelectricity. However, a new sample batch allows us to present results from EuO films with tensile strains up to 7 %.