Control of Switching Current Asymmetry by Magnetostatic Field in MgO-Based Magnetic Tunnel Junctions

Author

Lee, Kangho ; Kang, Seung H.

Author_Institution

Qualcomm Inc., San Diego, CA, USA

Volume

30

Issue

12

fYear

2009

Firstpage

1353

Lastpage

1355

Abstract

The inherent switching current asymmetry (beta) pertaining to ordinary magnetic tunnel junctions (MTJs) significantly reduces the write margin of spin-transfer-torque magnetoresistive random access memory (STT-MRAM). In this letter, we report how beta can be controlled by the effective magnetostatic field (H _e) that develops along the easy axis of the MTJs. As H _e is varied by 24% of the effective uniaxial anisotropy field, beta measured at 100 ns is reduced from 1.51 to 1.04. The results suggest that tuning the magnetostatic offset field (H _off) arising from the dipolar coupling between adjacent ferromagnetic layers can control beta and improve the write margin of STT-MRAM.

Keywords

II-VI semiconductors; MRAM devices; magnesium compounds; magnetic anisotropy; magnetic heads; tunnelling magnetoresistance; STT-MRAM; dipolar coupling; ferromagnetic layer; magnetic tunnel junction; magnetoresistive random access memory; magnetostatic field; spin-transfer-torque; switching current asymmetry control; uniaxial anisotropy field; write margin; Magnetic tunnel junction (MTJ) offset field; switching asymmetry; thermal stability;

fLanguage

English

Journal_Title

Electron Device Letters, IEEE

Publisher

ieee

ISSN

0741-3106

Type

jour

DOI

10.1109/LED.2009.2033129

Filename

5299266