Modified Martin-Puplett interferometer for magneto-optical Kerr effect measurements at sub-THz frequencies

TL;DR

This paper introduces a modified Martin-Puplett interferometer-based MOKE spectrometer capable of high-precision, broadband sub-THz measurements of Kerr effects in quantum materials at low temperatures and high magnetic fields.

Contribution

The paper presents a novel, versatile MOKE spectrometer that measures Kerr rotation and ellipticity simultaneously without reference calibration, suitable for quantum material studies.

Findings

Successful demonstration with an undoped InSb wafer

High accuracy in Kerr measurements without reference

Broad frequency range and low-temperature operation

Abstract

We present magneto-optical Kerr effect (MOKE) spectrometer based on a modified Martin-Puplett interferometer, utilizing continuous wave sub-THz low-power radiation in broad frequency range. This spectrometer is capable of measuring the frequency dependence of the MOKE response function, both the Kerr rotation and ellipticity, simultaneously with sub-milliradian accuracy without the need for reference measurement. The instrument's versatility allow it to be coupled to a cryostat with optical windows enabling studies of a variety of quantum materials such as unconventional superconductors, two-dimensional electron gas systems, quantum magnets, and other system showing optical Hall response, at sub-Kelvin temperatures and in high magnetic fields. We demonstrate the functionality of the MOKE spectrometer using an undoped InSb wafer as a test sample.