High-Speed Dynamics, Damping, and Relaxation Times in Submicrometer Spin-Valve Devices

Published

May 1, 2000

Author(s)

Stephen E. Russek, Shehzaad F. Kaka, Michael J. Donahue

Abstract

The dynamical response of spin-vale devices with linewidths of 0.8 5m has been measured after excitation with 160 ps magnetic impulses. The devices show resonant frequencies of 2-4 GHz which determine the upper limit of their operation frequency. The dynamical response can be fit with Landau-Lifshitz models to extract an effective uniform-mode damping constant, α_um. The measured values of α_um were between 0.04 and 0.01 depending on the magnitude of the longitudinal bias field. The appropriate damping coefficient for use in micromagnetic modeling, α_mn was extracted from the dynamical response with large longitudinal bias field. This value was used to model the switching of a 0.1 5m x 1.0 5m magnetoresistive random access memory cell. The micromagnetic model included shape disorder that is expected to be found in real devices. The simulations showed that, while the magnetization reverses rapidly (<0.5 ns), it took several nanoseconds for the energy to be removed from the magnetic system. The switching energy was stored in short wavelength magnetic fluctuations that could dramatically affect the re-reversal process 1-2 ns after the first reversal.

Citation

Journal of Applied Physics

Volume

87

Issue

9

Pub Type

Journals

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Keywords

damping, high-speed dynaics, landau-Fifshitz models, MRAM, spin-valve

Citation

Russek, S. , Kaka, S. and Donahue, M. (2000), High-Speed Dynamics, Damping, and Relaxation Times in Submicrometer Spin-Valve Devices, Journal of Applied Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=30205 (Accessed October 30, 2025)