Invited
Direct observation of electric- and magnetic- field induced switching of ferroelectricity in a room temperature magnetoelectric multiferroic
2Institute of Physics, University of Augsburg, Augsburg, Germany
3Department of Earth Sciences, University of Cambridge, Cambridge, UK
4Department of Physics and Institute of Multifunctional Materials, , University of Puerto Rico, San Juan, USA
5Materials Physics and Engineering Division, National Physical Laboratory, New Delhi, India
6Department of Physics, University of Warwick, Coventry, UK
7Department of Physics, University of Cambridge, Cambridge, UK
This talk is aimed as a tribute to Jim by highlighting one of his numerous achievements: he, and his team, were the first and (I believe) remain the only team to demonstrate the equivalent effects of electric- and magnetic- fields on the ferroelectric domain structure in a room temperature magnetoelectric multiferroic.
For any multiferroic device, there must be a coupling between the magnetic and electric orders. Such coupling has been shown at low temperature via both magnetic- and electric- switching, as far back as the 60s [1], however, it was not until 2006 that such a coupling was demonstrated at room temperature, when an electric field was used to switch antiferromagnetic domains [2]. There are now many excellent works expanding this to heterostructures at room temperature. Despite this progress, I believe, Jim’s team remains the only one to directly observe room-temperature switching of ferroelectric polarization with a magnetic field in single crystals [3-6].
In this talk, we use piezoresponse force microscopy to directly image the remnant ferroelectric domain states after applications of electric- and magnetic- fields, showing an equivalence of response. The coupling dynamics are illustrated by measuring capacitance as a function of magnetic field, which is analyzed using a ‘toy’ Landau theory. This shows the largest component is consistent with a linear magnetoelectric coupling. All our samples are single crystal lamella of (PbZr0.53Ti0.47O3)0.6-(PbFe0.5Ta0.5O3)0.4 cut from a bulk multiferroic ceramics [5] using a Focused Ion Beam. We finish by considering, conceptually, why these traits are so rare, and why they appear in this material.
[1] Ascher, et al., J. Appl. Phys. (1966)
[2] Zhao, et al., Nat. Mater. (2006)
[3] Evans, et al., Nat. Comms. (2013)
[4] Evans, et al., Phil. Trans. R. Soc. A (2014)
[5] Schiemer, et al., Adv. Funct. Mater. (2014)
[6] Evans, et al., Adv. Mater. (2015)
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