Simultaneous measurement of circular dichroism and Faraday rotation at terahertz frequencies using heterodyne detection

TL;DR

This paper introduces a highly accurate far-infrared system capable of simultaneously measuring complex Faraday angles, including rotation and ellipticity, across a broad THz spectral range and various materials.

Contribution

The work presents a novel heterodyne detection system that measures full complex Faraday angles with unprecedented precision over a wide spectral and temperature range.

Findings

Achieved 10 μrad/T measurement accuracy

Successfully measured diverse materials including superconductors and topological insulators

Operated across 0.3 to 6 THz spectral range and 10-310K temperatures

Abstract

A far-infrared system measures the full complex Faraday angle, rotation as well as ellipticity, with an unprecedented accuracy of 10\,$\mu$rad/T. The system operates on several far-infrared laser lines in the spectral range from 0.3 to 6 THz and produces results as a continuous function of temperature from 10 to 310K and applied fields between $\pm$ 8\,T. Materials successfully measured include GaAs 2-DEG heterostructures, various high temperature superconductors including Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$, Pr$_{2 - x}$Ce$_{x}$CuO$_4$, and La$_{2-x}$Sr$_x$CuO$_4$, and single crystals of the topological insulator Bi$_2$Se$_3$.