Research | Shi & Harumoto group

Perpendicular magnetic anisotropy (PMA) & Exchange bias: Towards the realization of Magnetoresistive Random Access Memory (MRAM), we are investigating PMA films and Exchange bias, which occurs in the interface between a ferromagnetic film and an antiferromagnetic film. (refs. Appl. Phys. Lett. 90 (2007) 212506, Acta Mater. 60 (2012) 6770, J. Appl. Phys. 113 (2013) 17D707, Phys. Rev. B 94 (2016) 054412, Phys. Rev. B 98 (2018) 144406, Sci. Adv. 5 (2019) aax4278)
Novel materials: We are also researching novel materials such as Mn4N, VO2, L11-CoPt for functional films. (refs. Mater. Lett. 311 (2022) 131615, Surf. Coat. Tech. 436 (2022) 128312, J. Magn. Magn. Mater. 471 (2019) 406). These days, we are interested in magnetic properties of High Entropy Alloy (HEA) films. (ref. J. Alloy. Compd. 938 (2023) 168533)
Memristor: Memristor is expected as a next generation component for data storage and operation. Using our thin-film technology, we are also trying to proposing the novel structure for Memristor application. (ref. Adv. Funct. Mater. 30 (2020) 2007101)
Magnetostriction or magnetoelastic effect: Magnetostriction means the dimension change during the magnetization of ferromagnetic materials. This phenomenon and its inverse phenomenon, namely inverse magnetostriction, can be applied to the energy conversion between mechanical and magnetic energies. (refs. J. Magn. Magn. Mater. 394 (2015) 349, J. Appl. Phys. 126 (2019) 083906)

Hydrogenation of films: Hydrogenation of the hydrogen-absorbing films is strongly influenced by the substrate (namely, substrate clamping effect). We are investigating its impact quantitatively. (refs. AIP Adv. 7 (2017) 065108, Int. J. Hydrogen Energy 45 (2020) 11662)
Property of metal hydrides: We have observed a novel property, or negative differential resistance (NDR), of metal hydride materials in 2023. (ref. Mater. Horizons 10 (2023) 5143)
Hydrogen sensors: We are seeking novel materials for hydrogen gas (H2) sensors and, also, trying to propose a detection algorithm for H2 detection. (refs. Int. J. Hydrogen Energy 46 (2021) 30204, Int. J. Hydrogen Energy 47 (2022) 34291, Award)

Reactive sputter deposition: The term “reactive sputter deposition” refers to the sputter deposition of compounds, such as oxides and nitrides, using a reaction between a metallic target and a gas like O2 and N2. We are employing this technology to deposit compound films. (refs. J. Appl. Phys. 113 (2013) 084306, J. Magn. Magn. Mater. 473 (2019) 490, Mater. Lett. 311 (2022) 131615)
Stress analysis of films: Diffraction stress analysis and substrate curvature.