H
H. Hasegawa
Researcher at Hitachi
Publications - 4
Citations - 1599
H. Hasegawa is an academic researcher from Hitachi. The author has contributed to research in topics: Tunnel magnetoresistance & Annealing (metallurgy). The author has an hindex of 3, co-authored 4 publications receiving 1447 citations.
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Journal ArticleDOI
Tunnel magnetoresistance of 604% at 300K by suppression of Ta diffusion in CoFeB∕MgO∕CoFeB pseudo-spin-valves annealed at high temperature
Shoji Ikeda,Jun Hayakawa,Yoshito Ashizawa,Y. M. Lee,Katsuya Miura,Katsuya Miura,H. Hasegawa,Masakiyo Tsunoda,F. Matsukura,Hideo Ohno +9 more
TL;DR: In this article, the authors observed tunnel magnetoresistance (TMR) ratio of 604% at 300K in Ta∕Co20Fe60B20∕MgO∕SiO2 or Co20Fe 60B20 ∕Ta pseudo-spin-valve magnetic tunnel junction junction annealed at 525°C.
Journal ArticleDOI
MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers
K. Mizunuma,Shoji Ikeda,J. H. Park,H. Yamamoto,Huadong Gan,Katsuya Miura,H. Hasegawa,Jun Hayakawa,Fumihiro Matsukura,Hideo Ohno +9 more
Abstract: The authors studied an effect of ferromagnetic (Co20Fe60B20 or Fe) layer insertion on tunnel magnetoresistance (TMR) properties of MgO-barrier magnetic tunnel junctions (MTJs) with CoFe/Pd multilayer electrodes TMR ratio in MTJs with CoFeB/MgO/Fe stack reached 67% at annealing temperature (Ta) of 200 °C and then decreased rapidly at Ta over 250 °C The degradation of the TMR ratio may be related to crystallization of CoFe(B) into fcc(111) or bcc(011) texture resulting from diffusion of B into Pd layers MTJs which were in situ annealed at 350 °C just after depositing bottom CoFe/Pd multilayer showed TMR ratio of 78% by postannealing at Ta=200 °C
Journal ArticleDOI
Tunnel magnetoresistance properties and film structures of double MgO barrier magnetic tunnel junctions
Huadong Gan,Shoji Ikeda,W. Shiga,Jun Hayakawa,Katsuya Miura,H. Yamamoto,H. Hasegawa,Fumihiro Matsukura,Tadakatsu Ohkubo,Kazuhiro Hono,Hideo Ohno +10 more
TL;DR: In this paper, double MgO barrier magnetic tunnel junctions (MTJ) with 3-nm-thick Co40Fe40B20 free layer were fabricated and annealed at 350°C.
Journal ArticleDOI
MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers
K. Mizunuma,Shoji Ikeda,J. H. Park,H. Yamamoto,Huadong Gan,Katsuya Miura,H. Hasegawa,Jun Hayakawa,Fumihiro Matsukura,Hideo Ohno +9 more
TL;DR: In this article, the effect of ferromagnetic (Co20Fe60B20 or Fe) layer insertion on tunnel magnetoresistance (TMR) properties of MgO-barrier magnetic tunnel junctions (MTJs) with CoFe/Pd multilayer electrodes was studied.