Chaos in nanomagnet via feedback current

Tomohiro Taniguchi, Nozomi Akashi, Hirofumi Notsu, Masato Kimura, Hiroshi Tsukahara, and Kohei Nakajima
Phys. Rev. B 100, 174425 – Published 21 November 2019
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Abstract

Nonlinear magnetization dynamics excited by spin-transfer effect with feedback current is studied both numerically and analytically. The numerical simulation of the Landau-Lifshitz-Gilbert equation indicates the positive Lyapunov exponent for a certain range of the feedback rate, which identifies the existence of chaos in a nanostructured ferromagnet. Transient behavior from chaotic to steady oscillation is also observed in another range of the feedback parameter. An analytical theory is also developed, which indicates the appearance of multiple attractors in a phase space due to the feedback current. An instantaneous imbalance between the spin-transfer torque and damping torque causes a transition between the attractors, and results in the complex dynamics.

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  • Received 31 August 2019
  • Revised 23 October 2019

DOI:https://doi.org/10.1103/PhysRevB.100.174425

©2019 American Physical Society

Physics Subject Headings (PhySH)

Nonlinear DynamicsCondensed Matter, Materials & Applied Physics

Authors & Affiliations

Tomohiro Taniguchi1, Nozomi Akashi2, Hirofumi Notsu3,4, Masato Kimura3, Hiroshi Tsukahara5, and Kohei Nakajima2

  • 1National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
  • 2Graduate School of Information Science and Technology, The University of Tokyo, Bunkyo-ku, 113-8656 Tokyo, Japan
  • 3Faculty of Mathematics and Physics, Kanazawa University, Kanazawa, Ishikawa 920-1164, Japan
  • 4JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
  • 5High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan

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Issue

Vol. 100, Iss. 17 — 1 November 2019

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