Optical Studies of Antiferromagnetism in Chromium and Its Alloys

Abstract

Absorption peaks are observed in the infrared spectra of chromium and of chromium alloys in the antiferromagnetic state. These peaks arise from the excitation of electrons across the antiferromagnetic energy gap. For the incommensurate state at low temperatures, the absorption maximum occurs at $5.1k{T}_{N}$. In the commensurate state, the gap is larger, and the absorption maximum is roughly independent of ${T}_{N}$. The breadth and temperature dependence of the absorption in pure chromium are explained on the basis of electron-phonon scattering. Resistivity measurements, optical-anisotropy data, and absorption spectra at several temperatures are presented and discussed.