Coherent microwave generation by spintronic feedback oscillator

Abstract

The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without the need of external spin torque injection. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000.

15 Pages, 6 Figures

References in corpus (3)

• Impact of the electrical connection of N Spin Transfer Oscillators on their synchronization : an analytical study
• Proposal for a Domain Wall Nano-Oscillator driven by Non-uniform Spin Currents
• Auto-oscillation threshold and line narrowing in MgO-based spin-torque oscillators

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• Straintronics: Manipulating the Magnetization of Magnetostrictive Nanomagnets with Strain for Energy-Efficient Applications
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• Resonant spin transfer torque nano-oscillators
• Integer, fractional and side band injection locking of spintronic feedback nano-oscillator to microwave signal
• Magneto Acoustic Spin Hall Oscillators
• High Frequency Microwave Emission of a Tri-layer Magnetic Tunnel Junction in the Absence of External Bias-Magnetic Field
• A magnetic domain wall Mackey-Glass oscillator
• Effects of delayed feedback on the power spectrum of spin-torque nano-oscillators
• Parametric mechanism of the magnetization reversal as a low-power recording mechanism for MRAM. Measurement of spin-accumulation-induced in-plane magnetic field in a FeB nanomagnet
• Generation of Multipeak Spectrum of Spin Torque Oscillator in Non-linear Regime
• Multiple modes of a single spin torque oscillator under the non-linear region