Interface effects in nanometer-thick yttrium iron garnet films studied by magneto- optical spectroscopy
Abstract
The properties of nanometer-thick yttrium iron garnet (YIG) films are strongly influenced by interfa-ces. This work employs spectral ellipsometry (SE) and magneto-optic polar Kerr rotation (PKR) to characterize YIG films with thickness,t, from 6 nm to 30 nm grown on Gd3Ga5O12(GGG) substrates oriented parallel to (111) plane.
The films display a surface roughness of 0.35 nm or lower. The analysis of the SE data at the photon energies of 1 eV<E<6.5 eV provided thet and permittivity values.
The PKR at 1.3 eV<E<4.5 eV is reasonably explained with the optical model for the YIG film/GGG substrate system. Even better agreement is achieved by assuming a 1.07-nm-thick layer sandwiched between YIG and GGG that has Fe3+ sublattice magnetization opposite to that in the YIG volume.
This suggests the existence of antiferromagnetic coupling between the Gd3+ and tet-rahedral Fe3+