Spin Dynamics and Transport Phenomena in Complex Magnetic Oxides

Computers and electronic devices are vital, but the power demands of Internet of Things (IoT) and artificial intelligence (AI) require new hardware solutions. With Moore's law approaching its limit, advancing beyond traditional CMOS transistors is essential.¹ A promising approach is encoding information through collective order parameters in innovative materials, such as using electric-field control of magnetism via multiferroics. In 2019, Intel proposed magnetoelectric spin-orbit (MESO) logic, embedding BiFeO₃ as a magnetoelectric medium, to overcome CMOS limitations for low-power and scalable AI hardware.² BiFeO₃ is one of the very few room-temperature magnetoelectric multiferroics, with its long-range antiferromagnetic spin cycloid coupled to its ferroelectric polarization. However, it exhibits a complex antiferromagnetic landscape in bulk single crystals³ or in thin films⁴ due to their multiple ferroelectric variants.

In this work, we simplified the multiferroic landscape in epitaxial BiFeO₃ thin films grown by pulsed laser deposition. We employed epitaxial engineering strategies including anisotropic strain⁵ and substrate vicinality approaches to stabilize single-domain ferroelectric (P) as well as spin cycloid propagation direction (k).⁶ Additionally, we were able to reversibly and deterministically manipulate the antiferromagnetic structure of BiFeO₃ by electric field between cycloidal and noncollinear G-type antiferromagnetic states.⁷ This heterostructures introduce convenient platform for magnetoelectric-based devices, advancing the development of MESO technology towards practical application.