Physical Review B

Electronic Raman studies of antiferromagnetic dysprosium aluminum garnet below TN and with and without an applied magnetic field

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Electronic Raman transitions within the H1526 and to the H1326 manifolds of antiferromagnetic dysprosium aluminum garnet (DyAlG) at 1.5 K (TN=2.5K) have been observed. Comparison of the Raman spectra obtained when a magnetic field (18 kOe) was applied along the [001] direction and when Happ=0 yielded estimations for the following: (a) the internal field splittings and consequently the exchange fields of the first two excited Kramers doublets in H1526; and (b) the Zeeman splittings of these levels. Using wave functions from our crystal-field analysis (Wadsack et al.), the g values of all the levels in the H1526 and H1326 manifolds have been calculated. These compared well with the g values previously observed (Aoyagi et al.) and with our Raman determination of gz=14.7±1 for the lowest level in H1326. Contributions to the electronic Raman scattering tensors from the six magnetic sublattices were derived for the applied field along [001] and for the different combinations of incident and scattered polarizations. Using the crystal-field wave functions for DyAlG, the relative Raman intensities for the observed Raman transitions were calculated. These Raman intensities are as sensitive to the crystal-field wave functions as are the g values. The calculated and observed Raman intensity ratios for various polarization combinations agreed only qualitatively. Breakdown of phonon polarization selection rules for the Eg and A1g, but not the T2g Raman-active phonons, was observed when Happ=18kOe. No explanation was given for this observation. © 1971 The American Physical Society.


01 Nov 1971


Physical Review B