Hyperfine Field in YIG with Charged Substitution

J. Kohouta, H. S̆tĕpánkováa, J. Englicha, P. Novákb, M. Kuc̆eraa and K. Nitschb a Faculty of Mathematics and Physics, Charles University 180 00 Prague 8, V Holešovičkách 2, Czech Republic bInstitute of Physics, Academy of Sciences Cukrovarnická 10, 16 253 Prague 6, Czech Republic

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57Fe NMR spectra were measured on thin films of yttrium iron garnet with divalent (Ca2+) and tetravalent (Ge4+) cation substitutions using the spin echo technique at 4.2 K. A series of Y3-xCaxFe5-xGexO12 samples with 0 ≤ x ≤ 0.0 5 was prepared by an epitaxial growth from BaO/B2O3/BaF2 flux on gadolinium gallium garnet substrate. Satellite lines corresponding to the iron ions having the Ge4+ and Ca2+ in their neighbourhood were identified. The sample with the germanium content of x(Ge) = 0.004 and (110) substrate orientation was used for a detailed study: NMR spectra of this sample were measured in an external magnetic field of 0.1 T applied along several directions in the plane of the film. The modification of the isotropic part and the anisotropy tensor of the hyperfine interaction caused by the Ge4+ substituent were obtained from the experimental data. The results were compared with those previously reported for trivalent substitution (Ga3+).

DOI: 10.12693/APhysPolA.97.519 PACS numbers: 76.60.-k, 75.50.Gg