Proposal for an active electromagnetic metamaterial based on spin-torque oscillators

Gen Tatara, Hiroaki T. Ueda, Katsuhisa Taguchi, Yuta Sasaki, Miyuki Nishijima, and Akihito Takeuchi
Phys. Rev. B 87, 155102 – Published 2 April 2013

Abstract

We propose theoretically an active material for electromagnetic radiation with frequency of GHz by use of spin-torque oscillators. The origin of the amplification is the energy supplied to the magnetization by the injected current. We show that close to a resonance with current-driven magnetization, the imaginary part of magnetic permeability becomes indeed negative for either of the two circular polarizations, resulting in a negative imaginary part of the refractive index. Besides, the real part of the refractive index is also manipulated by the current. Our system thus realizes an active filter to obtain circular polarized radiation and/or an electromagnetic metamaterial having negative refractive index, both controlled electrically.

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  • Received 6 December 2012

DOI:https://doi.org/10.1103/PhysRevB.87.155102

©2013 American Physical Society

Authors & Affiliations

Gen Tatara1,2, Hiroaki T. Ueda1,2, Katsuhisa Taguchi1, Yuta Sasaki1, Miyuki Nishijima1, and Akihito Takeuchi3

  • 1Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
  • 2RIKEN Center for Emergent Matter Science (CEMS) and RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
  • 3Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8656, Japan

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Issue

Vol. 87, Iss. 15 — 15 April 2013

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