Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer

Y. M. Lee; J. Hayakawa; S. Ikeda; F. Matsukura; H. Ohno

doi:10.1063/1.2234720

Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer

Y. M. Lee, J. Hayakawa, S. Ikeda, F. Matsukura, H. Ohno

Research output: Contribution to journal › Article › peer-review

139 Citations (Scopus)

Abstract

We investigated the relationship between tunnel magnetoresistance (TMR) ratio and the crystallization of CoFeB layers through annealing in magnetic tunnel junctions (MTJs) with MgO barriers that had CoFe/Ru/CoFeB synthetic ferrimagnet pinned layers with varying Ru spacer thickness (t_Ru). The TMR ratio increased with increasing annealing temperature (T_a) and t_Ru, reaching 361% at T_a=425°C, whereas the TMR ratio of the MTJs with pinned layers without Ru spacers decreased at T_a over 325°C. Ruthenium spacers play an important role in forming a (001)-oriented bcc CoFeB pinned layer, resulting in a high TMR ratio through annealing at high temperatures.

Original language	English
Article number	042506
Journal	Applied Physics Letters
Volume	89
Issue number	4
DOIs	https://doi.org/10.1063/1.2234720
Publication status	Published - 2006

ASJC Scopus subject areas

Physics and Astronomy (miscellaneous)

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10.1063/1.2234720

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title = "Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer",

abstract = "We investigated the relationship between tunnel magnetoresistance (TMR) ratio and the crystallization of CoFeB layers through annealing in magnetic tunnel junctions (MTJs) with MgO barriers that had CoFe/Ru/CoFeB synthetic ferrimagnet pinned layers with varying Ru spacer thickness (tRu). The TMR ratio increased with increasing annealing temperature (Ta) and tRu, reaching 361% at Ta=425°C, whereas the TMR ratio of the MTJs with pinned layers without Ru spacers decreased at Ta over 325°C. Ruthenium spacers play an important role in forming a (001)-oriented bcc CoFeB pinned layer, resulting in a high TMR ratio through annealing at high temperatures.",

author = "Lee, {Y. M.} and J. Hayakawa and S. Ikeda and F. Matsukura and H. Ohno",

note = "Funding Information: This work was supported by the IT-program of Research Revolution 2002 (RR2002): “Development of Universal Low-Power Spin Memory” from the Ministry of Education, Culture, Sports, Science and Technology of Japan.",

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T1 - Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer

AU - Lee, Y. M.

AU - Hayakawa, J.

AU - Ikeda, S.

AU - Matsukura, F.

AU - Ohno, H.

N1 - Funding Information: This work was supported by the IT-program of Research Revolution 2002 (RR2002): “Development of Universal Low-Power Spin Memory” from the Ministry of Education, Culture, Sports, Science and Technology of Japan.

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N2 - We investigated the relationship between tunnel magnetoresistance (TMR) ratio and the crystallization of CoFeB layers through annealing in magnetic tunnel junctions (MTJs) with MgO barriers that had CoFe/Ru/CoFeB synthetic ferrimagnet pinned layers with varying Ru spacer thickness (tRu). The TMR ratio increased with increasing annealing temperature (Ta) and tRu, reaching 361% at Ta=425°C, whereas the TMR ratio of the MTJs with pinned layers without Ru spacers decreased at Ta over 325°C. Ruthenium spacers play an important role in forming a (001)-oriented bcc CoFeB pinned layer, resulting in a high TMR ratio through annealing at high temperatures.

AB - We investigated the relationship between tunnel magnetoresistance (TMR) ratio and the crystallization of CoFeB layers through annealing in magnetic tunnel junctions (MTJs) with MgO barriers that had CoFe/Ru/CoFeB synthetic ferrimagnet pinned layers with varying Ru spacer thickness (tRu). The TMR ratio increased with increasing annealing temperature (Ta) and tRu, reaching 361% at Ta=425°C, whereas the TMR ratio of the MTJs with pinned layers without Ru spacers decreased at Ta over 325°C. Ruthenium spacers play an important role in forming a (001)-oriented bcc CoFeB pinned layer, resulting in a high TMR ratio through annealing at high temperatures.

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Giant tunnel magnetoresistance and high annealing stability in CoFeB/MgO/CoFeB magnetic tunnel junctions with synthetic pinned layer

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