Antiferromagnetic Resonance in NiO in Far-infrared Region

概要

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Using the far-infrared spectrometer constructed recently in Osaka University, measurements of the optical absorption were made on the single crystal of NiO (Neel temperature = 523°K) in the wave-length range of 210 to 385 microns and at temperatures 90° to 470°K. No magnetic field was applied. An absorption peak was clearly observed whose wave-length varied with temperature. With increasing temperature it shifted toward the longer wave-length side and at the same time the peak height diminished. At room temperature (291°K) the peak was at 293±5 microns (34.1±0.6cm^<-1>) and the wave-length value extrapolated to absolute zero was 274 microns (36.5cm^<-1>). This absorption peak is attributed to the antiferromagnetic resonance of the mode in which the antiparallel sublattice magnetizations oscillate perpendicularly to the easy plane of magnetization, (111). The constant, K, of the anisotropy energy which constrains the sublattice magnetizations in the easy plane is calculated to be 4.96 × 10^6 erg/cc at 0°K from the theoretical formula ω = (ge/2mc) (2K/X_1)^<1/2>, assuming g = 2.23. This can be compared with theoretical value, 7.01 × 10^6 erg/cc, based on the magnetic dipolar interaction between Ni^<++> ions, but the experimental value is smaller.
社団法人日本物理学会の論文
1960-11-05