Topological Magnetic Textures by Design

Magnetic Skyrmions are smoothly varying local spin arrangement of size ranging from 10 to 100 nm. From theoretical simulations, these quasiparticles are known to have several attractive properties. On the other hand, there are multiple degrees of freedom in magnetic oxides but absent in metallic ferromagnets, such as multiferroicity and magnetoelectric coupling that offer a way to control magnetism. Hence, stabilizing magnetic Skyrmion in oxides may prove advantageous. In the past, magnetic oxides are known to be majority antiferromagnetic and have few practical applications. In the recent years, however, the concept of antiferromagnetic spintronic begins receiving attention and appreciation because of the insensitivity of antiferromagnets to a stray magnetic field that would enhance the reliability of data storage devices.

In this work, we demonstrate that we can utilize charge transfer induced interface ferromagnetism as a robust tool to widen the accessible material choices where topologically protected spin textures, or magnetic Skyrmions, can be stabilized. We became the first to understand that Skyrmions can be stabilized by interfacial charge transfer between a paramagnet with strong spin-orbit coupling (SOC) exemplified by CaIrO3 and an antiferromagnet exemplified by CaMnO3. Such an effect is absent in individual bulk materials. This concept can potentially be generalized to many more antiferromagnetic-paramagnetic oxide combinations; hence Skyrmions with practical characteristics can be tailored, such as the occurrence at high temperature, low magnetic field, and small Skyrmion size for practical memory applications. We also hope to demonstrate magnetoelectric coupling in oxide Skyrmions in the future.