Maximum Detected Frequency of a Detector of Terahertz Frequency Signals based on an Antiferromagnetic Tunnel Junction

摘要

Terahertz-frequency (TF) electromagnetic radiation has great potential for use in medical, security, industry, and science applications. However, many problems concerning the generation, detection, and processing of quasimonochromatic TF signals have not been solved yet. In this paper we present analysis of the noise properties of a TF signal detector (TFD) based on a dc-biased antiferromagnetic tunnel junction (ATJ) consisting of two outer platinum layers and an inner antiferromagnet/MgO bilayer. The proposed antiferromagnetic (AFM) detector has the upper-frequency limit $mathrm{f}_{max}$, as the magnitude of the generated output dc voltage decreases with the increase of the frequency of the applied TF signal. Hence, if the frequency of the input TF signal exceeds a certain value $mathrm{f}_{max}$, the detected voltage $U_{mathrm{d}mathrm{c}}$ decreases below the Johnson-Nyquist (JN) noise voltage $U_{mathrm{J}mathrm{N}}$, and the signal detection is impossible. By considering a simple electric scheme of the TFD we show the maximum detected frequency of 0. 3S THz can be reached in the case of a thin MgO tunneling barrier ($sim$1nm), and the optimum lateral size of the ATJ equal to a $sim$300nm.