Electric control of Magnetism

Nowadays, magnetism and electricity in solids are utilized for every aspect of modern technology. Usually, the magnetism is affected by magnetic field, and the electricity is by electric field. In contrast, electric control of magnetism and magnetic control of electricity are called “magnetoelectric effect”, and considered as a key to realize novel electronic device with unique function and low energy consumption.

Among several approaches proposed for electric control of magnetism, I have focused on the search of “multiferroics” i.e. materials characterized by both magnetic and dielectric orders. Magnetic materials ubiquitously host spin orbit interaction, i.e. an intrinsic force to connect the electric and magnetic aspect of electron; When its effect is accentuated under the specific symmetry of crystal, the unprecedentedly large and versatile magnetoelectric effect can be obtained.

I’ve been searching for such new multiferroics, and trying to observe novel magnetoelectric coupling phenomena through various dielectric / magnetic / optical measurements. Their underlying physics are also investigated with microscopic probes such as electron microscope or diffraction experiments; The obtained results are feed-backed to the design of new multiferroic materials more suitable for the practical application.

Major Achievements:

  • Discovery of skyrmions (particle-like spin vortices) in multiferroics
  • Discovery of ferroelectricity driven by 120 degree spin texture on triangular lattice
  • Observation of “electromagnon (electrically-driven magnetic excitation)” with relativistic origin
  • Realization of magnetic switching of ferroelectric domain with non-volatile and multiple-valued nature
  • Discovery of multiferroicity in halides (such as CuCl2 and MnI2)