Interfacial and Bulk Magnetic Properties of Stoichiometric Cerium Doped Terbium Iron Garnet Polycrystalline Thin Films

Abstract

One of the best magneto-optical claddings for optical isolators in photonic integrated circuits is sputter deposited cerium-doped terbium iron garnet (Ce:TbIG) which has a large Faraday rotation (≈−3500° cm −1 at 1550 nm). Near-ideal stoichiometryCe Tb Fe 0.57 + + = =       of Ce 0.5 Tb 2.5 Fe 4.75 O 12 is found to have a 44 nm magnetic dead layer that can impede the interaction of propagating modes with garnet claddings. The effective anisotropy of Ce:TbIG on Si is also important, but calculations using bulk thermal mismatch overestimate the effective anisotropy. X-ray diffraction measurements yield highly accurate measurements of strain that show anisotropy favors an in-plane magnetization in agreement with the positive magnetostriction of Ce:TbIG. Upon doping TbIG with Ce, a slight decrease in compensation temperature occurs which points to preferential rare-earth occupation in dodecahedral sites and an absence of cation redistribution between different lattice sites. The high Faraday rotation, large remanent ratio, large coercivity, and preferential in-plane magnetization enable Ce:TbIG to be an in-plane latched garnet, immune to stray fields with magnetization collinear to direction of light propagation.

High Figure of Merit Magneto‐Optical Ce‐ and Bi‐Substituted Terbium Iron Garnet Films Integrated on Si

“…[ 29] CeTbIG films with Ce substituting up to 25% of the Tb sites showed a Faraday rotation above −3200 ± 200° cm −1 , [ 31,32 ] but a 44 nm thick magnetic dead layer formed between the waveguide and the CeTbIG, hindering the interaction of evanescent light with the MO garnet cladding. [ 32 ] However, the optical absorption and FoM of these Bi‐ and Ce‐substituted TbIG materials have not yet been reported.…”

“…[29] CeTbIG films with Ce substituting up to 25% of the Tb sites showed a Faraday rotation above −3200 ± 200° cm −1 , [31,32] but a 44 nm thick magnetic dead layer formed between the waveguide and the CeTbIG, hindering the interaction of evanescent light with the MO garnet cladding. [32] However, the optical absorption and FoM of these Bi-and Cesubstituted TbIG materials have not yet been reported.In this paper, we report the growth, magnetic, and optical characteristics of polycrystalline thin films of TbIG, CeTbIG, and BiTbIG synthesized using pulsed laser deposition (PLD) on Films of polycrystalline terbium iron garnet (TbIG), cerium-substituted TbIG (CeTbIG), and bismuth-substituted TbIG (BiTbIG) are grown on Si substrates by pulsed laser deposition. The films grow under tensile strain due to thermal mismatch with the Si substrate, resulting in a dominant magnetoelastic anisotropy which, combined with shape anisotropy, leads to in-plane magnetization.…”

“…[29][30][31][32][33][34] Sputtered BiTbIG with Bi substitution of 14% of the Tb sites has a Faraday rotation of ≈−500° cm −1 at 1550 nm, [29] the same sign as that of CeYIG, which at 1550 nm wavelength had a Faraday rotation of at least −3700° cm −1 . [29] CeTbIG films with Ce substituting up to 25% of the Tb sites showed a Faraday rotation above −3200 ± 200° cm −1 , [31,32] but a 44 nm thick magnetic dead layer formed between the waveguide and the CeTbIG, hindering the interaction of evanescent light with the MO garnet cladding. [32] However, the optical absorption and FoM of these Bi-and Cesubstituted TbIG materials have not yet been reported.In this paper, we report the growth, magnetic, and optical characteristics of polycrystalline thin films of TbIG, CeTbIG, and BiTbIG synthesized using pulsed laser deposition (PLD) on Films of polycrystalline terbium iron garnet (TbIG), cerium-substituted TbIG (CeTbIG), and bismuth-substituted TbIG (BiTbIG) are grown on Si substrates by pulsed laser deposition.…”

“…[23][24][25] Bi-substituted TbIG has been grown by liquidphase epitaxy and flux methods [23][24][25][26][27] or sol-gel methods, [28] and more recently thin films of Ce-and Bi-substituted TbIG (CeTbIG, BiTbIG) were grown on Si by sputtering. [29][30][31][32][33][34] Sputtered BiTbIG with Bi substitution of 14% of the Tb sites has a Faraday rotation of ≈−500° cm −1 at 1550 nm, [29] the same sign as that of CeYIG, which at 1550 nm wavelength had a Faraday rotation of at least −3700° cm −1 . [29] CeTbIG films with Ce substituting up to 25% of the Tb sites showed a Faraday rotation above −3200 ± 200° cm −1 , [31,32] but a 44 nm thick magnetic dead layer formed between the waveguide and the CeTbIG, hindering the interaction of evanescent light with the MO garnet cladding.…”

“…[29][30][31][32][33][34] Sputtered BiTbIG with Bi substitution of 14% of the Tb sites has a Faraday rotation of ≈−500° cm −1 at 1550 nm, [29] the same sign as that of CeYIG, which at 1550 nm wavelength had a Faraday rotation of at least −3700° cm −1 . [29] CeTbIG films with Ce substituting up to 25% of the Tb sites showed a Faraday rotation above −3200 ± 200° cm −1 , [31,32] but a 44 nm thick magnetic dead layer formed between the waveguide and the CeTbIG, hindering the interaction of evanescent light with the MO garnet cladding. [32] However, the optical absorption and FoM of these Bi-and Cesubstituted TbIG materials have not yet been reported.…”