ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Rocksalt structure solid solutions were prepared by coevaporating Eu2O3 and Tb metal. The films have the general formula Eu1−xTbxO1−y(D'Alembertian)y where y, the oxygen vacancy fraction, is given by y=(3x−1)/2. We have also prepared Tb-doped EuS solid solutions where y(approximately-equal-to)x so we can compare the effects of anion vacancies in both the oxide and sulfide systems. The coercivity, Hc, increases rapidly with Tb doping at about x=0.15 in the sulfide system and x=0.45 in the oxide system. The Hc of both systems falls on a universal curve, however, when plotted vs vacancies/RE ((D'Alembertian)/RE) with the rapid increase occurring at (D'Alembertian)/RE=0.15. This value is close to 1/6 (0.166) which in octahedral coordination corresponds to one anion vacancy/RE. This suggests that the near neighbor vacancy is producing a strong crystal field at the Tb site which causes strong single ion anisotropy and thus a high coercivity. The MO spectra of the oxides show a strong dependence on x. At x=0.25, peaks are observed at 1.5 eV (−3°), 2.2 eV (5.5°), and 2.7 eV (−2°). At x=0.33, the spectra change completely. A narrow peak with a rotation θK=−20° appears at 2.5 eV, dominating the spectrum. The reflectivity, R, goes through a sharp minimum at the same energy (R〈1%), possibly causing the enhancement in θK.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.352717
