Fabrication and magnetic properties of Ce1Y2Fe5O12 thin films on GGG and SiO2/Si substrates

New Magneto‐Optical Film of Ce,Ga:GIG with High Performance

“…In Ce:GIG film, part of Ce 3+ ion is oxidized to Ce 4+ ion and then precipitate in the form of CeO 2 . The precipitation of CeO 2 would further result in the excess of Fe 3+ ion in film, which finally precipitates as γ‐Fe 2 O 3 impurity phase . In order to inhibit the oxidation of Ce 3+ ion and reduce the stress level of annealed film, a two‐step annealing method that as‐deposited film firstly was annealed at 700°C in nitrogen atmosphere and then annealed at 500°C in air atmosphere was carried out in this article (hereafter expressed as two‐step method).…”

“…Owing to the transition between Ce 3+ (4 f ) and Fe 3+ (3 d ) tetrahedral states enabled by the charge transfer from Ce 3+ ion to Fe 3+ ion, the magneto‐optical performance of GIG film can be greatly improved by doping Ce 3+ ion into GIG . However, Ce 3+ ion is easily oxidized to Ce 4+ ion which is not helpful for improving the magneto‐optical performance . In view of this, the valence states of Ce in Ce,Ga:GIG films were analyzed by Ce 3 d XPS spectra.…”

“…The precipitation of CeO 2 would further result in the excess of Fe 3+ ion in film, which finally precipitates as c-Fe 2 O 3 impurity phase. 24 In order to inhibit the oxidation of Ce 3+ ion and reduce the stress level of annealed film, a twostep annealing method that as-deposited film firstly was annealed at 700°C in nitrogen atmosphere and then annealed at 500°C in air atmosphere was carried out in this article (hereafter expressed as two-step method). The purpose of second step of annealing at 500°C temperature in air is to oxidize most of Fe 2+ ion to Fe 3+ ion while few Ce 3+ ion is oxidized, which was verified as an effective method because no CeO 2 diffraction peaks emerged in the XRD patterns of film annealed by two-step method.…”

“…In addition, the magnetization of Ce,Ga:GIG film directly annealed at 700°C in air is larger than annealed by two‐step method, which may be contributed to the existence of γ‐Fe 2 O 3 impurity phase in the former film . Because M s Value of γ‐Fe 2 O 3 is much higher than that of Ce:GIG, even a small amount of γ‐Fe 2 O 3 existing in thin film would also make M s Value of thin film increase significantly.…”

“…27 However, Ce 3+ ion is easily oxidized to Ce 4+ ion which is not helpful for improving the magneto-optical performance. 24,28 In view of this, the valence states of Ce in Ce, Ga:GIG films were analyzed by Ce 3d XPS spectra.…”