Abstract-Magnetic Modulation of Terahertz Waves via Spin-Polarized Electron Tunneling Based on Magnetic Tunnel Junctions

Zuanming Jin, Jugeng Li, Wenjie Zhang, Chenyang Guo, Caihua Wan, Xiufeng Han, Zhenxiang Cheng, Chao Zhang, Alexey V. Balakin, Alexander P. Shkurinov, Yan Peng, Guohong Ma, Yiming Zhu, Jianquan Yao, and Songlin Zhuang

https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.14.014032

Magnetic tunnel junctions (MTJs) are a key technology in modern spintronics because they are the basis of read-heads of modern hard disk drives, nonvolatile magnetic random access memories, and sensor applications. In this paper, we demonstrate that tunneling magnetoresistance can influence terahertz (THz) wave propagation through a MTJ. In particular, various magnetic configurations between parallel state and antiparallel state of the magnetizations of the ferromagnetic layers in the MTJ have the effect of changing the conductivity, making a functional modulation of the propagating THz electromagnetic fields. Operating in the THz frequency range, a maximal modulation depth of 60% is reached for the parallel state of the MTJ with a thickness of 77.45 nm, using a magnetic field as low as 30 mT. The THz conductivity spectrum of the MTJ is governed by spin-dependent electron tunneling. It is anticipated that the MTJ device and its tunability scheme will have many potential applications in THz magnetic modulators, filtering, and sensing.

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