Far‐Infrared Reflectivity of Optical Magnons in FeF₂ and CoF₂

Abstract

Antiferromagnetic optical magnons are observed by means of their far-infrared reflectivity for the first time. The structure of these "magnetic reststrshlenbands" is calculated approximately for normal incidence of the infrared radiation. Spin wave damping can be taken into account by introducing complex eigenfrequencies. The tensor elements of the frequency dependent complex magnetic permeability fulfill a generalized Kurosawa relation.Es werden erstmals antifenomagnetische optische Magnonen aufgrund ihres Reflexionsvermogens im fernen Infraroten beobachtet. Die Struktur dieser ,,magnetischen Reststrahlenbanden" wird fiir senkrechten Lichteinfall niiherungsweise berechnet. Die Diimpfung der Spinwellen liiBt sich dabei iiber den Ansatz komplexer Eigenfrequenzen berlicksichtigen. Die Tensorelemente der frequenzabhangigen, komplexen magnetischen Permeabilitiit geniigen einer verallgemeinerten Kurosaws-Relation.

Optical spectroscopy in CoO: Phononic, electric, and magnetic excitation spectrum within the charge-transfer gap

“…Therefore, we assign these features to MD transitions. Note that similar observations of MD transition have been reported by Häusler et al 62 for the related compound CoF 2 , where Co has the same electronic configuration as in CoO. While M 1 − M 4 only appear far below T N , the peaklike transitions Q 1 − Q 3 do not show any significant changes at T N and are, obviously, not related to ͑͒ but contribute to ͑͒.…”

Optical Spectroscopy in CoO: Phonons, Electric, and Magnetic Excitations

“…Therefore, we assign these features to MD transitions. Note that similar observations of MD transition have been reported by Häusler et al 61 for the related compound CoF 2 , where Co has the same electronic configuration as in CoO. While M 1 − M 4 only appear far below T N , the peak-like transitions Q 1 − Q 3 do not show any significant changes at T N and are, obviously, not related to µ(ω) but contribute to ε(ω).…”

Theory of a gyromagnetic Fabry - Pérot resonator

“…However, modern FIR Fourier-transform spectrometers are able to produce frequency-scan spectra down to about 10 cm −1 with dielectric beam splitters or about 2 cm −1 with wire-grid beam splitters [13]. As reviewed elsewhere [4], starting with the work of Häussler et al [14,15] on FeF 2 and CoF 2 , a substantial number of frequency-scanned spectra have been published with resolution now down to about 0.02 cm −1 [16].…”