Submillimeter backward-wave oscillator spectroscopy of the rare-earth orthoferrites

Abstract

The complex dielectric permittivity and the complex magnetic permeability of the orthoferrites RFeO/sub 3/ (R=Y, Tm, Dy, Gd, Ho, Er, Tb) and Y/sub 1-x/Lu/sub x/FeO/sub 3/ have been investigated at submillimeter wavelengths v=100-1000 GHz. The parameters of the two antiferromagnetic resonance modes (resonance frequencies, linewidths, and mode contributions to the static permeability) have been obtained. The authors observed the electronic transitions inside the TM/sup 3+/, Er/sup 3+/, Ho/sup 3+/ ground multiplets and found a strong influence of this excitation on the AFMR mode behavior. A permittivity increase (up to 30%) in TmFeO/sub 3/ resulting from the electrodipolar transitions in Tm/sup 3+/ was observed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>