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Title: Large-amplitude, narrow-linewidth microwave emission in a dual free-layer MgO spin-torque oscillator

Synchronized magnetization motion among the several magnetic layers composing a spin-torque oscillator (STO) is considered an effective way to improve spectral purity. To utilize this scheme in a MgO-based STO, we have fabricated a dual free-layer STO composed of a CoFeB free layer (FL), a MgO barrier layer, and a CoFe/Ru/CoFeB synthetic ferrimagnet free layer (SyF). Unlike conventional MgO-based STOs, this structure does not have an antiferromagnetic layer that pins the SyF, leading to a large-amplitude oscillation of magnetization in the SyF. The dual free-layer STO exhibits coherent microwave emissions with power spectrum density beyond 800 nW/GHz and narrow spectral linewidth below 5 MHz (Q-factor ≈ 2000). Macrospin simulations confirm that the stable oscillations originate from the synchronized magnetization motion of the FL and the SyF through dynamical dipolar coupling.
Authors:
; ; ; ;  [1]
  1. Corporate Research and Development Center, Toshiba Corporation, Kawasaki 212-8582 (Japan)
Publication Date:
OSTI Identifier:
22391908
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ANTIFERROMAGNETISM; BORON COMPOUNDS; COBALT COMPOUNDS; DEPLETION LAYER; IRON COMPOUNDS; MAGNESIUM OXIDES; MAGNETIZATION; OSCILLATIONS; OSCILLATORS; RUTHENIUM; SIMULATION; SPIN