Spin-dependent optical transitions in yttrium iron garnet

Abstract

This study reviewed the electronic structure using density functional theory (DFT) and demostrated the transmission of optical magnetic circular spectrum in probing spin-dependent optical transitions in yttrium iron garnet (YIG). DFT + U results suggested that the t _2 orbital of tetrahedral irons are polarized by exchange-splitting O(2 p ) bands. Such polarization was found to be essential for the kinetic exchange and magnetism in YIG. DFT + U results also identified the spin-polarized energy gaps in YIG. On the basis of the distinctions of Fe _3 O _4 [J. Chen et al , Phys. Rev. B , 98 , 085 141 (2018)] and YIG in electronic band features along with their manifestations in an optical magnetic circular diachroism (OMCD) spectrum, a map of spin-dependent optical transitions in YIG is presented. Based on the analysis of OMCD spectra at room temperature, the majority-spin and minority-spin gap in YIG are determined to be 2.45 and 2.25 eV, respectively.

Keywords

• First-principle calculation
• Electronic structure
• Faraday effect
• Superexchange
• Ferrimagnetic