Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions

H. D. Gan; H. Sato; M. Yamanouchi; S. Ikeda; K. Miura; R. Koizumi; F. Matsukura; H. Ohno

doi:10.1063/1.3671669

Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions

H. D. Gan, H. Sato, M. Yamanouchi, S. Ikeda, K. Miura, R. Koizumi, F. Matsukura, H. Ohno

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53 Citations (Scopus)

Abstract

We have investigated a tunnel magnetoresistance (TMR) ratio of CoFeB/MgO perpendicular magnetic tunnel junctions (p-MTJs) with a 40 nm diameter as a function of an annealing temperature T _a. The TMR ratio at room temperature (RT) increases with increasing T _a and reaches 149 at T _a = 350 °C, and further increase of T _a results in a strong reduction of the TMR ratio, i.e., 2 at T _a = 400 °C. The temperature dependence of the junction resistance versus magnetic field loops reveals that the reduced TMR ratio at RT is due to the disappearance of a stable antiparallel magnetization configuration. We find that reduction of dipole coupling restores the TMR ratio.

Original language	English
Article number	252507
Journal	Applied Physics Letters
Volume	99
Issue number	25
DOIs	https://doi.org/10.1063/1.3671669
Publication status	Published - 2011 Dec 19

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title = "Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions",

abstract = "We have investigated a tunnel magnetoresistance (TMR) ratio of CoFeB/MgO perpendicular magnetic tunnel junctions (p-MTJs) with a 40 nm diameter as a function of an annealing temperature T a. The TMR ratio at room temperature (RT) increases with increasing T a and reaches 149 at T a = 350 °C, and further increase of T a results in a strong reduction of the TMR ratio, i.e., 2 at T a = 400 °C. The temperature dependence of the junction resistance versus magnetic field loops reveals that the reduced TMR ratio at RT is due to the disappearance of a stable antiparallel magnetization configuration. We find that reduction of dipole coupling restores the TMR ratio.",

author = "Gan, {H. D.} and H. Sato and M. Yamanouchi and S. Ikeda and K. Miura and R. Koizumi and F. Matsukura and H. Ohno",

note = "Funding Information: The authors thank I. Morita, T. Hirata, H. Iwanuma, and R. Sasaki for technical support in MTJ fabrication. This work was supported in part by the FIRST program of JSPS and the GCOE program at Tohoku University.",

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T1 - Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions

AU - Gan, H. D.

AU - Sato, H.

AU - Yamanouchi, M.

AU - Ikeda, S.

AU - Miura, K.

AU - Koizumi, R.

AU - Matsukura, F.

AU - Ohno, H.

N1 - Funding Information: The authors thank I. Morita, T. Hirata, H. Iwanuma, and R. Sasaki for technical support in MTJ fabrication. This work was supported in part by the FIRST program of JSPS and the GCOE program at Tohoku University.

PY - 2011/12/19

Y1 - 2011/12/19

N2 - We have investigated a tunnel magnetoresistance (TMR) ratio of CoFeB/MgO perpendicular magnetic tunnel junctions (p-MTJs) with a 40 nm diameter as a function of an annealing temperature T a. The TMR ratio at room temperature (RT) increases with increasing T a and reaches 149 at T a = 350 °C, and further increase of T a results in a strong reduction of the TMR ratio, i.e., 2 at T a = 400 °C. The temperature dependence of the junction resistance versus magnetic field loops reveals that the reduced TMR ratio at RT is due to the disappearance of a stable antiparallel magnetization configuration. We find that reduction of dipole coupling restores the TMR ratio.

AB - We have investigated a tunnel magnetoresistance (TMR) ratio of CoFeB/MgO perpendicular magnetic tunnel junctions (p-MTJs) with a 40 nm diameter as a function of an annealing temperature T a. The TMR ratio at room temperature (RT) increases with increasing T a and reaches 149 at T a = 350 °C, and further increase of T a results in a strong reduction of the TMR ratio, i.e., 2 at T a = 400 °C. The temperature dependence of the junction resistance versus magnetic field loops reveals that the reduced TMR ratio at RT is due to the disappearance of a stable antiparallel magnetization configuration. We find that reduction of dipole coupling restores the TMR ratio.

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Origin of the collapse of tunnel magnetoresistance at high annealing temperature in CoFeB/MgO perpendicular magnetic tunnel junctions

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