Eur. Phys. J. B 21, 159-161 (2001)
https://doi.org/10.1007/s100510170191

Optical measurements of the superconducting gap in MgB₂

¹ 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
² Laboratory of Solid State Physics, Materials Science Centre, Nijenborgh 4, 9747 AG Groningen, The Netherlands
³ Department of Physics, Aoyama-Gakuin University, 6-16-1 Chitsedai, Setagaya-ku, Tokyo 157, Japan

Corresponding author: ^a dressel@pi1.physik.uni-stuttgart.de

Received: 7 March 2001
Revised: 18 April 2001
Published online: 15 May 2001

Abstract

Far-infrared reflectivity studies on the polycrystalline intermetallic compound MgB₂ with a superconducting transition temperature K were performed at temperatures 20 K to 300 K. We observe a significant raise of the superconducting-to-normal state reflectivity ratio below , with a maximum at about , which gives a lower estimate of the superconducting gap of meV.