Topologically protected unidirectional magntoelectric switching in multiferroic GdMn2O5
2Institute of Solid State Physics, Technical University of Vienna, Vienna, Austria
3Department of Physics and Astronomy, Rutgers University, Piscataway NJ, USA
4Zernike Institute of Advanced Materials, University of Groningen, Groningen, Netherlands
Electric control of magnetism and magnetic control of ferroelectricity can improve energy
efficiency of magnetic memory and data processing devices. However, the necessary
magnetoelectric switching is hard to achieve, and requires more than just a coupling between
spin and charge degrees of freedom. We show [1] that an application and subsequent removal of
a magnetic field reverses the electric polarization of the multiferroic GdMn2O5, thus
requiring two cycles to bring the system back to the original configuration. During this
unusual hysteresis loop, four states with different magnetic configurations are visited by the
system, with one half of all spins undergoing unidirectional full-circle rotation in increments
of ∼90o. Therefore, GdMn2O5 acts as a magnetic crankshaft converting the back-and-forth
variations of the magnetic field into a circular spin motion. This peculiar four-state
magnetoelectric switching emerges as a topologically protected boundary between different
two-state switching regimes. Our findings establish a paradigm of topologically protected
switching phenomena in ferroic materials.
[1] L. Ponet et al., Nature 607, 81 (2022)
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