In our laboratory, we are conducting research on device materials to dramatically improve the memory application characteristics of magnetoresistive device junctions, which are representative of charge-spin coupled devices, under Grant-in-Aid for Scientific Research (S). A magnetoresistive element is a layered element in which insulators, semiconductors, and metals are sandwiched between conductive thin films that have magnetic properties. When the intermediate layer is an insulator, it is called a magnetic tunnel junction, and when the intermediate layer is a conductor, it is also called a giant magnetoresistive element. Each layer is several to several tens of nanometers thick. When a voltage is applied to the upper and lower conductors of the intermediate layer, a current flows, and the electrical resistance of the element changes depending on whether the magnetization (direction of the magnetic poles) of the upper and lower magnets is parallel or antiparallel. It is also called a TMR element or a GMR element because it exhibits a giant magnetoresistance effect (GMR effect). These elements are applied to magnetic sensors and magnetic heads of hard disks, and have become one of the spintronics devices that are indispensable in modern society.
In our laboratory, in order to realize the next generation nanoscale magnetoresistive memory, we are promoting research and development of "perpendicular magnetization" magnetoresistive elements using group IV, oxide, nitride semiconductors and manganese magnetic materials.
This research is being conducted jointly with Professor Hamaya of Osaka University, who is a world leader in the field of semiconductor spintronics.

Main achievements

Tunnel magnetoresistance exceeding 100% in magnetic tunnel junctions using Mn-based tetragonal alloy electrodes with perpendicular magnetic anisotropy,
Kazuya Z. Suzuki, Shigemi Mizukami,
AIP Advances, 13 035225-1-035225-7 (2023).
https://doi.org/10.1063/5.0141706

Tracing magnetic atom diffusion with annealing at the interface between CoMn alloy and MnGa layer by X-ray magnetic circular dichroism
J. Okabayashi, K. Z. Suzuki, S. Mizukami
Journal of Magnetism and Magnetic Materials 564, 170163 (2022)
https://www.sciencedirect.com/science/article/pii/S0304885322010484