Far-Infrared Optical Absorption of Manganese Fluoride

Abstract

Optical absorption in MnF2 in the region from 50 to 350 cm−1 was studied. A search was made in particular for multiple-magnon processes previously reported in the literature. While, for example, four-magnon processes can be obtained theoretically from an expansion of the Heisenberg spin Hamiltonion, we found no temperature dependent absorption in the region studied other than the well-known two-magnon peak at 100 cm−1. All the observed peaks above 100 cm−1 could be attributed to phonons.