Controlling the Topologically-Protected Magnetoelectric Switching in Multiferroic GdMn₂O₅

Manipulating magnetic moments by electric fields has been an everlasting goal for fundamental research. Recently, we could demonstrate a peculiar magnetoelectric behavior in multiferroic GdMn₂O₅ showing a switching through a cycle of four states when the magnetic field is ramped up and down [1]. In this sequence, half of the spins undergo a rotation of about 90° each time the magnetic field is ramped leading to a full-circle 360° rotation when applying and removing a magnetic field two times in a series. GdMn₂O₅ thus 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 two different series, 1→2→3→4→1 and 1→4→3→2→1, respectively.<br/>Further on, in a certain range of experimental parameters the 4-state sequence becomes topologically trivial. In this regime, the external electric field adds a key parameter of the switching. We show that in such case the electric voltage allows a full control over the four magnetoelectric states in GdMn₂O₅.<br/><br/>[1] L. Ponet, S. Artyukhin, Th. Kain, J. Wettstein, Anna Pimenov, A. Shuvaev, X. Wang, S.-W. Cheong, M. Mostovoy, and A. Pimenov, "Topologically protected magnetoelectric switching in a multiferroic", Nature <b>607</b>, 81 (2022). https://rdcu.be/ddZaF