Growth-Induced Order by Site-Preference in Anisotropic Mixed Rare-Earth Iron Garnet Thin Films

Magnetic properties of rare-earth iron garnets can be dramatically changed by mixing different ions on a single site in the crystal structure. We observe and characterize ordering of rare-earth ions due to site-preference in mixed europium-thulium iron garnet (EuTmIG) thin films grown by pulsed laser deposition (PLD) on (111) gadolinium gallium garnet (GGG). EuTmIG thin films with increasing Eu fraction (x) show linear strain variation from tensile to compressive due to lattice mismatch on GGG. In addition, a large anisotropy in the form K
G
= K(x)(1-x) is observed and identified as growth-induced anisotropy (GIA), which is great enough in intermediate Eu:Tm compositions to overcome shape and magnetoelastic anisotropy and generate perpendicular magnetic anisotropy (PMA). Spin-Hall magnetoresistance measurements show that GIA in PLD films (80 kJ/ m
³
) is five times greater than that observed in liquid-phase grown garnets. Atomic resolution h scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy (EDS) prove that GIA is caused by local atom ordering described by site symmetry reduction due to the projected face view during growth (site-preference model). This work shows that modern growth and characterization techniques enable understanding and control of atomic matter enabling one to engineer magnetic properties in complex oxides.