Atomic-scale insight into lattice and electronic modulation induced by the substitution of bismuth in iron garnet with enhanced magneto-optical effect

In this study, Bismuth substituted lutetium iron garnet prepared by liquid epitaxial method shows large faraday rotation up to 1.64 degree/µm at 633nm at room temperature, whose structure variation and element distribution in atomic scale have been directly interpreted by using analytical scanning transmission microscopy (STEM). The substituted Bismuth located in dodecahedral site of lutetium iron garnet can induced the change of lattice and furtherly will lead to the distortion of octahedral Fe sites, but magnetic order is not modified, which is all verified by using energy loss spectrum (EELS). Combined with density function theory (DFT) calculation, distorted octahedral magnetic sublattice contributes to the reduced crystal field splitting energy and orbital degeneracy.
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