Giant Zeeman shifts in the optical transitions of yttrium iron garnet thin films

We report the observation of giant Zeeman shifts in the optical transitions of high-quality very thin films of yttrium iron garnet ( YIG) grown by rf sputtering on gadolinium gallium garnet substrates. The optical absorption profile measured with magneto-optical absorption spectroscopy shows dual optical transition in the UV-visible frequency region attributed to transitions from the O-2p valence band to the Fe-3d conduction band and from the O-2p valence band to Fe-2p(5)3d(6) excitonic states at the Gamma-symmetry point of the YIG band structure. The application of a static magnetic field of only 0.6 kOe produces giant Zeeman shifts of similar to 100 meV in the YIG band structure and similar to 60 meV in the excitonic states corresponding to effective g-factors on the order of 10(4). The giant Zeeman effects are attributed to changes in energy levels by the large exchange fields of the Fe-3d orbitals during the magnetization process. Published by AIP Publishing.