Spatially resolving spin texture control and manipulation in ferroic heterostructures*

Complex oxides offer possibilities to engineer spin textures via their many degrees of freedom, and have been proposed for use in energy efficient magneto-electric spin-orbit logic architectures.¹ Recent antiferromagnetic (AFM) spintronics work has focused on ultrafast magnetization dynamics geometries with no stray field.² However, lack of stray field makes AFM domain structure imaging difficult though conventional imaging techniques. I will discuss the use of X-ray photoemission electron microscopy (PEEM) with both x-ray linear and circular dichroism to spatially and chemically resolve shape- and voltage-controlled ferroic order in heterostructures of AFM, ferroelectric(FE), and ferromagnetic (FM) layers including (La,Sr)FeO₃^3,4, and CoFe/(La,Bi)FeO₃⁵.
I will show that direct control over spin textures is possible through many routes. Lateral confinement tailors the easy axis orientation in (La,Sr)FeO₃ wires as edge-induced anisotropy in microstructures can induce nearly-single domain states,³ and in the limit of few unit-cell thick layers, the AFM spin axis lies in the plane of the film in contrast to thicker layers whose AFM spin axis cants out of plane.⁴ Furthermore, magneto-electric switching energy density can be scaled through careful engineering in a BiFeO₃-based system towards 10 µJ cm^-2 at a switching field of 200 mV.⁵ Coupling at these interfaces allows for mutual control of the domain structure via a variety of pathways, including shape anisotropy and magneto-electric interactions, and thus offers additional degrees of freedom towards low-energy AFM-based spintronics.

1. Manipatruni et al, Nature 565 35 (2018).
2. Baltz et al, Rev. Mod. Phys 90, 015005 (2018).
3. Bang, RVC et al, Appl. Phys. Lett 115 112403 (2019).
4. Lee, RVC et al, J. Appl. Phys 127, 203901 (2020).
6. Prasad, RVC et al, Adv. Mat. 2001943 (2020).