2012/12/06 by Gen Tatara, Hiroaki Ueda, Hiroaki T. Ueda +4
Engineering · Materials Science · Physics and Astronomy · #Advanced Antenna and Metasurface Technologies #Condensed matter physics #Electromagnetic radiation #Magnetic field #Magnetic properties of thin films #Magnetization #Metamaterial #Metamaterials and Metasurfaces Applications #Optics #Physics #Quantum mechanics #Refractive index #Torque #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.87.155102
published as Physical Review B Vol.87, No.15,155102(2013)
arxiv created 2012/12/06 · openalex publication_date 2013/04/02 · arxiv updated 2013/04/04 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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.