Low-temperature far-infrared ellipsometry of convergent beam

TL;DR

This paper develops a specialized ellipsometry technique for low-temperature, far-infrared measurements on small samples, providing a comprehensive approach including theoretical solutions and experimental validation.

Contribution

It introduces a novel convergent beam ellipsometry method tailored for low-temperature far-infrared studies on small samples, addressing both theoretical and experimental challenges.

Findings

Measured dielectric functions of materials at various wavelengths and temperatures.

Validated the ellipsometry method with experimental results on gold, SrTiO3, and YBa2Cu3O7-delta.

Provided temperature-dependent optical properties relevant for condensed matter research.

Abstract

Development of an ellipsometry to the case of a coherent far infrared irradiation, low temperatures and small samples is described, including a decision of the direct and inverse problems of the convergent beam ellipsometry for an arbitrary wavelength, measurement technique and a compensating orientation of cryostat windows. Experimental results are presented: for a gold film and UBe13 single crystal at room temperature (lambda=119 um), temperature dependencies of the complex dielectric function of SrTiO3 (lambda=119, 84 and 28 um) and of YBa2Cu3O7-delta ceramic (lambda=119 um).