Far Infrared Optical Absorption in Manganese Fluoride

Abstract

<p> The optical absorption in manganese fluoride has been studied in the range of 30 to 300 cm^-1 with emphasis placed on the possible multiple magnon absorptions (other than two-magnon) and an induced single magnon absorption. It is shown that theoretically one can expect four-magnon processes by expanding the Heisenberg spin hamiltonian to higher orders in the creation and annihilation operators introduced by the Holstein-Primakoff transformation. However, neither an induced one magnon nor four magnon process was observed. The absorptions which were seen in the spectra were attributed to phonon processes.</p>