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Published on: May 19, 2014
Spin-torque shot noise in magnetic tunnel junctions
A L Chudnovskiy1, J Swiebodzinski, A Kamenev
1I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstrasse 9, D-20335 Hamburg, Germany.
Physical Review Letters
|September 4, 2008
Summary
Spin-polarized current transfers angular momentum to ferromagnets, causing spin-torque. Nonequilibrium shot noise introduces stochastic forces, leading to a nonmonotonic linewidth dependence on current in ferromagnetic dynamics.
Area of Science:
- Condensed matter physics
- Spintronics
- Magnetism
Background:
- Spin-polarized currents can exert torques on ferromagnetic materials.
- Electrical current inherently contains shot noise, a source of fluctuations.
- Understanding current-induced effects in ferromagnets is crucial for device applications.
Purpose of the Study:
- To investigate the influence of current-induced shot noise on ferromagnetic dynamics.
- To develop a theoretical framework incorporating stochastic forces into magnetization dynamics.
- To analyze the impact of nonequilibrium noise on the precession spectrum linewidth.
Main Methods:
- Derivation of a stochastic Landau-Lifshitz-Gilbert equation.
- Solution of the associated Fokker-Planck equation.
- Analysis of the magnetization dynamics under spin-torque and stochastic forces.
Main Results:
- A stochastic model for magnetization dynamics was established.
- The Fokker-Planck equation revealed the role of nonequilibrium noise.
- A nonmonotonic dependence of the precession spectrum linewidth on current was demonstrated.
Conclusions:
- Nonequilibrium shot noise significantly affects ferromagnetic dynamics.
- The interplay between spin-torque and noise leads to complex behaviors.
- Theoretical predictions provide insights into current-driven magnetic phenomena.
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