Topologically protected magnetoelectric switching in a multiferroic

• Published in: Nature (London) Vol. 607; no. 7917; pp. 81 - 85
• Main Authors: Ponet, Louis, Artyukhin, S., Kain, Th, Wettstein, J., Pimenov, Anna, Shuvaev, A., Wang, X., Cheong, S.-W., Mostovoy, Maxim, Pimenov, Andrei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07.07.2022; Nature Publishing Group
• Subjects: 639/301/119/2792; 639/766/119/996; Configurations; Data processing; Electric control; Electric polarization; Energy efficiency; Ferroelectricity; Humanities and Social Sciences; Hysteresis loops; Magnetic control; Magnetic fields; Magnetism; multidisciplinary; Multiferroic materials; Science; Science & Technology - Other Topics; Science (multidisciplinary); Simulation; Switching; Symmetry
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-04851-6

Electric control of magnetism and magnetic control of ferroelectricity can improve the energy efficiency of magnetic memory and data-processing devices 1 . However, the necessary magnetoelectric switching is hard to achieve, and requires more than just a coupling between the spin and the charge degrees of freedom 2 – 5 . Here we show that an application and subsequent removal of a magnetic field reverses the electric polarization of the multiferroic GdMn 2 O 5 , 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 about 90 degrees. Therefore, GdMn 2 O 5 acts as a magnetic crankshaft that converts 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. The electric polarization of a multiferroic is reversed by the application and subsequent removal of a magnetic field, resulting in topologically protected unidirectional magnetoelectric switching.