Pulsed laser deposited Y3Fe5O12 films: Nature of magnetic anisotropy II

Abstract

Recently we found epitaxial Fe-deficient yttrium iron garnet Y3Fe5−tO12−3t/2 (YIG) films pulsed laser deposited onto the (111) and (001) face of Gd3Ga5O12 single crystal experience, respectively, strong rhombohedral and tetragonal distortions and possess unusual magnetic anisotropy. Using the crystal field theory, we explained these anomalies and showed in YIG(111) films ferric ion vacancies preferentially occupy octahedral complexes, order themselves along the [111] growth direction, cause rhombohedral lattice distortions, generate strong uniaxial and significantly reduce cubic crystalline anisotropy, Manuilov et al., [J. Appl. Phys. 106, 123917 (2009)]. Oxygen vacancies govern electrical neutrality and in spite of high concentration (in access of 7 at. %) they are perfectly ordered that is indicated by narrow ferromagnetic resonance linewidth. The present paper aims to compare growth anisotropies induced in (111) and (001) epitaxial Fe-deficient YIG films. Ordering of vacancies appeared to be different in (111) and (001) oriented YIG films. In highly Fe-deficient YIG(001) we found much smaller imbalance in redistribution of vacancies between the octa- and tetrahedral magnetic sublattices. This feature together with a weaker crystal field in tetrahedral Fe3+–O2− complexes result in reduced growth induced magnetic anisotropy in (001) oriented tetragonal distorted YIGs compared to rhombohedral distorted YIG(111) films.