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

Research output: Contribution to journalArticlepeer-review

46 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 languageEnglish
Article number252507
JournalApplied Physics Letters
Volume99
Issue number25
DOIs
Publication statusPublished - 2011 Dec 19

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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