Theory of Antiferromagnet-Based Detector of Terahertz Frequency Signals

Abstract

We present a theory of a detector of terahertz-frequency signals based on an antiferromagnetic (AFM) crystal. The conversion of a THz-frequency electromagnetic signal into the DC voltage is realized using the inverse spin Hall effect in an antiferromagnet/heavy metal bilayer. An additional bias DC magnetic field can be used to tune the antiferromagnetic resonance frequency. We show that if a uniaxial AFM is used, the detection of linearly polarized signals is possible only for a non-zero DC magnetic field, while circularly polarized signals can be detected in a zero DC magnetic field. In contrast, a detector based on a biaxial AFM can be used without a bias DC magnetic field for the rectification of both linearly and circularly polarized signals. The sensitivity of a proposed AFM detector can be increased by increasing the magnitude of the bias magnetic field, or by by decreasing the thickness of the AFM layer. We believe that the presented results will be useful for the practical development of tunable, sensitive and portable spintronic detectors of THz-frequency signals based of the antiferromagnetic resonance (AFMR).

Strongly nonlinear antiferromagnetic dynamics in high magnetic fields

“…where characteristic frequencies are defined as follows: ω ex = γH ex , ω EA = γH EA , ω HA = γH HA , H ex is the AFM internal exchange magnetic field, H e , H h and e EA = x, e HA = z are the AFM anisotropy easy and hard fields and unit vectors, respectively [24,43]. The corresponding values of all the constants listed in the paper are given in the table below.…”

Spin-orbit torque manipulation of sub-terahertz magnons in antiferromagnetic α-Fe2O3

“…However, attention has principally been confined to manipulating the static magnetic state, leading to AFM magnetic reorientation/switching [11][12][13][14] . In stark contrast, the direct control of the THz spin dynamics in antiferromagnets, such as the magnon frequency, is critical for novel applications such as THz spin nanooscillators [15][16][17] and rectifiers [18][19][20][21] . Pioneering efforts to control the magnon frequency have focused on conventional ferromagnetic and ferrimagnetic thin films and two-dimensional exfoliated flakes, whose magnon frequencies reside in tens of GHz [22][23][24][25][26][27][28] .…”

Advances in Antiferromagnetic Spintronics

“…Safin et al discussed a new model for detecting THz frequency signals using antiferromagnetic resonance [13]. The conversion of an electromagnetic signal in THz frequency into a direct current (DC) voltage was calculated and found to be achievable via the inverse spin Hall effect in an antiferromagnet/heavy metal bilayer.…”