Frequency-assisted current-distribution effect in magnetic tunnel junction

Author

Chang, Y.M. ; Li, K.S. ; Tong, S.Y. ; Tung, M.J. ; Lin, Minn-Tsong

Author_Institution

Dept. of Phys. & Center for Nanostorage Res., Nat. Taiwan Univ., Taipei, Taiwan

fYear

2005

fDate

4-8 April 2005

Firstpage

485

Lastpage

486

Abstract

Magnetoimpedance effects were studied in a series of magnetic tunnel junctions by means of the 4-terminal measurement. Magnetic tunnel junctions (MTJ) of layered structure NiFe/CoFe/Al₂O₃/CoFe were prepared in a magnetron sputtering system with base pressure better than 3×10^-8 torr. The study of magnetoimpedance effects were carried out with Angilent 4284A precision LCR meter at room temperature. The values of the real-part impedance were found to change their signs as the sensing frequency increased. At certain critical sensing frequency, a giant percentage change under sweeping magnetic field was obtained. This abnormal behavior is explained by the picture of frequency-assisted inhomogeneous current distribution effect, in which the effective tunnel resistance is tuned at the variation of sensing frequency.

Keywords

aluminium compounds; cobalt alloys; interface structure; iron alloys; magnetic multilayers; nickel alloys; sputtered coatings; tunnelling magnetoresistance; 3E-8 torr; 4-terminal measurement; 5 min; Angilent 4284A precision LCR meter; NiFe-CoFe-Al₂O₃-CoFe; frequency-assisted current-distribution effect; magnetic tunnel junctions; magnetoimpedance effects; magnetron sputtering system; real-part impedance; room temperature; sensing frequency; sweeping magnetic field; tunnel resistance; Capacitance; Current distribution; Frequency; Impedance; Magnetic field measurement; Magnetic materials; Magnetic tunneling; Physics; Plasma temperature; Tunneling magnetoresistance;

fLanguage

English

Publisher

ieee

Conference_Titel

Magnetics Conference, 2005. INTERMAG Asia 2005. Digests of the IEEE International

Print_ISBN

0-7803-9009-1

Type

conf

DOI

10.1109/INTMAG.2005.1463671

Filename

1463671