Title :
High Level Oscillations With Narrow Linewidth in Magnetic Nano-Contact Spin Torque Oscillator With Synthetic AF Spin-Valve Structure
Author :
Endo, Hiroaki ; Tanaka, Toshiyuki ; Doi, Masaaki ; Hashimoto, Susumu ; Fuke, Hiromi Niu ; Iwasaki, Hitoshi ; Sahashi, Masashi
Author_Institution :
Dept. of Electron. Eng., Tohoku Univ., Sendai, Japan
Abstract :
We investigated the current induced magnetization dynamics, so called spin torque oscillation, in magnetic nano-contact MR element with a synthetic antiferromagnetic type spin-valve structure under high in-plane applied magnetic field of 0.9-1 kOe. Very high level oscillation of 18 nVHz-1/2 with narrow FWHM of 12 MHz was observed in the condition of negative applied current where electron-spin is injected from free layer to reference one. Applied current dependency on an oscillation frequency is a blueshift with good linearlity, and same dependency on level and FWHM is almost constant in the range of -10 to -14 mA, while applied field dependency on frequency shows redshift with two different slopes, -2.5 MHz/Oe in less than 1 kOe and -8.7 MHz/Oe in more than 1 kOe which field is smaller than the spin-flop field for the synthetic antiferromagnet, besides very clear and reasonable peak and bottom for oscillation level and FWHM are observed, respectively. It is thought that these magnetization dynamics are originated from synthetic antiferromagnet.
Keywords :
antiferromagnetic materials; magnetic microwave devices; magnetisation; microwave oscillators; nanomagnetics; spin polarised transport; spin valves; blueshift; current induced magnetization dynamics; electron-spin injection; frequency 12 MHz; high level microwave oscillations; in-plane applied magnetic field; magnetic nanocontact spin torque oscillator; redshift; spin-flop field; synthetic antiferromagnetic spin-valve structure; Magnetic nano-contact magnetoresistance; magnetization dynamics; microwave oscillation; spin transfer torque; synthetic antiferromagnet;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2009.2023851