Comment on 'The role of Bi~(3+) ions in magneto-optic Ce and Bi comodified epitaxial iron garnet films'

摘要

In a recent publication, Hwang and coauthors show the data measured with two thin-film devices that were grown with pulsed laser deposition (PLD) and claim to have gained an understanding of the role of Bi ions corresponding to the large magneto-optical Faraday rotations (MOFR) in the near infrared exhibited in these films. The latter has been first observed in PLD epitaxial iron garnet films doped with Bi and Ce grown on gadolinium-gallium-oxide substrates.2 The main two claims in the paper are that (1) the presence of Bi~(3+) ions increases the concentration of Ce~(3+) ions and (2) Bi~(3+) induces a less strained lattice of higher quality. The first conclusion is not appropriate, as demonstrated below, and its relevance to the large MOFR exhibited by these crystals is unclear.