Abstract-Terahertz frequency spectrum analysis with a nanoscale antiferromagnetic tunnel junction

Journal of Applied Physics

Sulymenko,  S. Louis, J. Li,  R. S. Khymyn, E. Bankowski,  T. Meitzler,  V. S. Tyberkevych,  A. N. Slavin,  O. V. Prokopenko,

(a) Pt/AFM/MgO/Pt antiferromagnetic tunnel junction (ATJ). The driving dc current Idrive(t)$I_{\mathrm{drive}}(t)$ flowing in the bottom Pt layer of an ATJ generates the transverse spin current ISH$I_{\mathrm{SH}}$ flowing into the AFM layer, which excites the TF rotation of magnetization of the AFM sublattices and, consequently, the TF variations of the junction resistance R(t)$R(t)$. When a TF signal with power Ps$P_s$ and frequency fs$f_s$ is supplied to the junction, its action results in the generation of voltage Uatj$U_{\mathrm{atj}}$ across the whole structure. (b) A simplified equivalent electric scheme of the ATJ-based detector connected through an ideal bias tee to a source of an external TF signal.

https://aip.scitation.org/doi/10.1063/1.5140552

A method to perform spectrum analysis on low power signals between 0.1$0.1$ and 10 THz is proposed. It utilizes a nanoscale antiferromagnetic tunnel junction (ATJ) that produces an oscillating tunneling anisotropic magnetoresistance, whose frequency is dependent on the magnitude of an evanescent spin current. It is first shown that the ATJ oscillation frequency can be tuned linearly with time. Then, it is shown that the ATJ output is highly dependent on matching conditions that are highly dependent on the dimensions of the dielectric tunneling barrier. Spectrum analysis can be performed by using an appropriately designed ATJ, whose frequency is driven to increase linearly with time, a low pass filter, and a matched filter. This method of THz spectrum analysis, if realized in the experiment, will allow miniaturized electronics to rapidly analyze low power signals with a simple algorithm. It is also found by simulation and analytical theories that for an ATJ with a 0.09μm2$0.09\mu {\mathrm{m}}^2$ footprint, spectrum analysis can be performed over a 0.25THz$0.25\mathrm{THz}$ bandwidth in just 25 ns on signals that are at the Johnson–Nyquist thermal noise floor.