Control of magnetization dynamics by substrate orientation in YIG thin films

Abstract

Yttrium Iron Garnet (YIG) and bismuth (Bi) substituted YIG (Bi0.1Y2.9Fe5O12, BYG) films are grown in-situ on single crystalline Gadolinium Gallium Garnet (GGG) substrates [with (100) and (111) orientations] using pulsed laser deposition (PLD) technique. As the orientation of the Bi-YIG film changes from (100) to (111), the lattice constant is enhanced from 12.384 Å to 12.401 Å due to orientation dependent distribution of Bi3+ ions at dodecahedral sites in the lattice cell. Atomic force microscopy (AFM) images show smooth film surfaces with roughness 0.308 nm in Bi-YIG (111). The change in substrate orientation leads to the modification of Gilbert damping which, in turn, gives rise to the enhancement of ferromagnetic resonance (FMR) line width. The best values of Gilbert damping are found to be (0.54 ± 0.06) × 10−4, for YIG (100) and (6.27 ± 0.33) × 10−4, for Bi-YIG (111) oriented films. Angle variation (ϕ) measurements of the Hr are also performed, that shows a four-fold symmetry for the resonance field in the (100) grown film. In addition, the value of effective magnetization (4πMeff) and extrinsic linewidth (ΔH0) are observed to be dependent on substrate orientation. Hence PLD growth can assist single-crystalline YIG and BYG films with a perfect interface that can be used for spintronics and related device applications.

Growth parameters of Bi0.1Y2.9Fe5O12 thin films for high frequency applications

“…Lattice constant slightly increases with the increase in thickness of the film in the case of (111) as compared to (100). Since the distribution of Bi 3+ in the dodecahedral site is dependent on the substrate orientation [7,23,29], the (111) oriented films show an increase in the lattice constant. In Bi-YIG films, this slight increase in the lattice constant (in the 111 direction) leads to a comparatively larger lattice mismatch as seen in Fig.…”

“…One of the most important magnetic materials for studying high frequency magnetization dynamics is the Yttrium Iron Garnet (YIG, Y3Fe5O12). Thin film form of YIG have attracted a huge attention in the field of spintronic devices due to its large spin-wave propagation length, high Curie temperature Tc ≈ 560 K [1], lowest Gilbert damping and strong magneto-crystalline anisotropy [2][3][4][5][6][7]. Due to these merits of YIG, it finds several applications such as in magnetooptical (MO) devices, spin-caloritronics [8,9], and microwave resonators and filters [10][11][12][13][14].…”

“…In Wyckoff notation, the yttrium (Y) ions are located at the dodecahedral 24c sites, whereas the Fe ions are located at two distinct sites; octahedral 16a and tetrahedral 24d. The oxygen ions are located in the 96h sites [7]. The ferrimagnetism of YIG is induced via a super-exchange interaction at the 'd' and 'a' site between the non-equivalent Fe 3+ ions.…”

“…It has already been observed that substituting Bi/Ce for Y in YIG improves magneto-optical responsivity [13,[15][16][17][18][19][20][21]. In addition, Bi substitution in YIG (Bi-YIG) is known to generate growth-induced anisotropy, therefore, perpendicular magnetic anisotropy (PMA) can be achieved in Bi doped YIG, which is beneficial in applications like magnetic memory and logic devices [7,22,23]. Due to its usage in magnon-spintronics and related disciplines such as caloritronics, the study of fundamental characteristics of Bi-YIG materials is of major current interest due to their high uniaxial anisotropy and Faraday rotation [17,[24][25][26][27].…”

Oxidic 2D Materials

“…Epitaxial single crystalline YIG thin films can be deposited on ( 111)-oriented GGG (Figure 3b,c) or other garnet substrates at different temperatures via sputtering processes [168]. The stabilization of the garnet phase and an increase in transmittance via doping to improve the material's magneto-optical performance [171] as well as possibilities to control perpendicular magnetic anisotropy [172] and magnetization dynamics by substrate orientation [173] have recently been demonstrated. Kotov et al, achieved an important step towards the fabrication of high-performance ultra-thin garnet films by using magnetron sputtering deposition and crystallization annealing for the growth of magneto-optical bismuth-substituted iron-garnet films [174].…”