Control of magnetization dynamics by substrate orientation in YIG thin films

TL;DR

This study investigates how substrate orientation affects the magnetic properties of YIG and Bi-YIG thin films grown on GGG substrates, revealing orientation-dependent variations in lattice structure, damping, and resonance behavior relevant for spintronics.

Contribution

It demonstrates that substrate orientation influences the magnetic damping and resonance characteristics of YIG and Bi-YIG films, providing insights for optimizing spintronic device interfaces.

Findings

Lattice constant increases with (111) orientation

Gilbert damping varies significantly with substrate orientation

Resonance field exhibits four-fold symmetry in (100) 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 {\AA} to 12.401 {\AA} 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)*10-4, for YIG (100) and (6.27)*10-4, for Bi-YIG (111) oriented films. Angle variation 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 (4{\pi}Meff) and extrinsic linewidth ({\Delta}H0) 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.