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

• Published in: Applied physics letters 2016-09, Vol.109 (12)
• Main Authors: Vidyasagar, R., Alves Santos, O., Holanda, J., Cunha, R. O., Machado, F. L. A., Ribeiro, P. R. T., Rodrigues, A. R., Mendes, J. B. S., Azevedo, A., Rezende, S. M.
• Format: Article
• Language: English
• Subjects: Applied physics; Band structure; Band structure of solids; Conduction bands; Energy levels; Gadolinium; Gadolinium-gallium garnet; Iron; Magnetism; Optical transition; Substrates; Thin films; Valence band; Yttrium; Yttrium-iron garnet
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4962830

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 53d 6 excitonic states at the Γ-symmetry point of the YIG band structure. The application of a static magnetic field of only 0.6 kOe produces giant Zeeman shifts of ∼100 meV in the YIG band structure and ∼60 meV in the excitonic states corresponding to effective g-factors on the order of 104. 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.