Title :
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
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;
Conference_Titel :
Magnetics Conference, 2005. INTERMAG Asia 2005. Digests of the IEEE International
Print_ISBN :
0-7803-9009-1
DOI :
10.1109/INTMAG.2005.1463671
