Frontier Research Institute for Interdisciplinary Sciences
Tohoku University

Nano-granular magnetic films have been extensively studied partly due to their brilliant chemical stability and unique functionality. By varying the concentration of granules, various intriguing functionalities have been found. In particular, materials exhibiting a tunnel magnetoresistance (TMR) effect are widely used for applications as magnetic sensors.

In 2014, with further reducing the content of granules, a new kind of magnetoelectric effect, i.e. tunneling magneto-dielectric (TMD) effect was discovered at room temperature; this may open the door of development of the devices that exhibits multiple functions. I proposed a new sputtering method, i.e. co-separate sputtering, to achieve clear interface between the granule and matrix, wherein the sputtering plasma of metal and ceramic is separated by adding a partition while retaining the high sputtering rate with rotating the substrate. The as-deposited nanocomposites exhibit enhanced TMD effect in contrast to the previous method. Besides, I have achieved 8-fold enhancement of TMD response via a balanced control of super-paramagnetic and ferromagnetic components. However, exploration of device application with TMD effect is none.

In recent year, faced with the increase of aging population, the demand for medical and nursing care as well as for miniaturized, high-performance extracorporeal biosensors has been growing rapidly. In this research, I will challenge the application of TMD effect by interdisciplinary research involving biomedical engineering, materials science, and applied physics. Specifically, the aim of this research is to create new gradient granular films for wide-frequency TMD effect for unique novel biosensor devices.