Electric field control of magnetic domains in Y-type hexaferrite single crystals at room temperature

In the trigonal Y-type hexaferrites the magnetoelectric properties are attributed to the emergence of the so-called FE3 phase with co-existing ferrimagnetic and ferroelectric orders [1]. Recently, in the Al-doped Y-type hexaferrite, (Ba,Sr)₂Co₂Fe₁₁AlO₂₂, this multiferroic phase has been observed as a metastable phase close to room temperatures even in the absence of magnetic field [2,3].
In this presentation we report that in bulk Ba_0.8Sr_1.2Co₂Fe_12-xAl_xO₂₂ with x=0.9, the ferrimagnetic and ferroelectric domains have considerable coupling even at room temperature. Cross-control of the magnetic and electric degrees of freedoms, i.e. the direct (P-H) and inverse (M-E) magnetoelectric effect have been observed up to room temperature. Using magnetic force microscopy, control of the magnetic domain pattern by the application of electric field is directly visualized. We demonstrate that magnetization switching is realized via the propagation of two kinds of domain walls; parallel and perpendicular to the applied electric field.
[1] T. Kimura, Ann. Rev. Condens. Matter Phys. 3, 93-110 (2012).
[2] S. Hirose et. al., APL 104, 022907 (2014).
[3] T. Nakajima et. al., PRB 94 195154 (2016).