Epitaxial growth of Y3Fe5O12 thin films with perpendicular magnetic anisotropy

Abstract

Here, we report the realization of epitaxial Y3Fe5O12 (YIG) thin films with perpendicular magnetic anisotropy (PMA). The films are grown on the substituted gadolinium gallium garnet substrate (SGGG) by pulsed laser deposition. It was found that a thin buffer layer of Sm3Ga5O12 (SmGG) grown on top of SGGG can suppress the strain relaxation, which helps induce a large enough PMA to overcome the shape anisotropy in YIG thin films. The reciprocal space mappings analysis reveals that the in-plane strain relaxation is suppressed, while the out-of-plane strain relaxation exhibits a strong dependence on the film thickness. We found that the PMA can be achieved for both bilayer (YIG/SmGG) and tri-layer (SmGG/YIG/SmGG) structural films with YIG layer thicknesses up to 20 nm and 40 nm, respectively.

Static and Dynamic Magnetic Properties of Single‐Crystalline Yttrium Iron Garnet Films Epitaxially Grown on Three Garnet Substrates

“…In epitaxial films, magnetoelastic anisotropy can be tuned via the lattice mismatch with the substrate. Although YIG has only a modest magnetostriction, PMA was reported for 20 nm thick epitaxial YIG on a Sm 3 Ga 5 O 12 (SmGG) buffer layer on a rare‐earth‐substituted gadolinium gallium garnet (SGGG) substrate and for SGGG/SmGG/40 nm thick YIG/SmGG, in which the top SmGG suppresses strain relaxation. The top SmGG was essential to obtain PMA in >40 nm thick YIG, but such overlayers lead to spacing loss which would decrease the efficiency of SW excitations using an antenna.…”

“…[22] However, films of low anisotropy materials such as YIG and Permalloy are typically magnetized in plane due to the dominant shape anisotropy and require a substantial external outof-plane magnetic field to saturate the film. Although YIG has only a modest magnetostriction, PMA was reported for 20 nm thick epitaxial YIG on a Sm 3 Ga 5 O 12 (SmGG) buffer layer on a rare-earth-substituted gadolinium gallium garnet (SGGG) substrate and for SGGG/SmGG/40 nm thick YIG/SmGG, [23] in which the top SmGG suppresses strain relaxation. [9] In epitaxial films, magnetoelastic anisotropy can be tuned via the lattice mismatch with the substrate.…”

Low damping and microstructural perfection of sub-40nm-thin yttrium iron garnet films grown by liquid phase epitaxy

“…A general description for magnetic garnets has been given for example by Hansen [94]. Applied to thick [43,64] as well as to thin epitaxial iron garnet films (see, e.g., [37,56,59,60,62]), the out-of-plane uniaxial anisotropy field H 2⊥ is mainly determined by the magnetocrystalline and uniaxial anisotropy contributions. While the former refers to the direction of magnetization to preferred crystallographic directions in the cubic garnet lattice, the latter originates from lattice strain and growth conditions.…”

“…Refs. [58][59][60][61][62]). Between these two extremes are YIG LPE films, which are usually grown on standard GGG substrates and exhibit small tensile strain if no lattice misfit compensation, e.g.…”

Magnetism and spin transport in rare-earth-rich epitaxial terbium and europium iron garnet films

“…YIG films typically exhibit an in-plane easy axis dominated by shape anisotropy, although there are reports of thin YIG films showing PMA [12][13][14]. Other FMI films have been grown with PMA, notably barium hexaferrite (BaFe 12 O 19 , BaM) grown epitaxially on sapphire with anisotropy field of 17 kOe [4,15]; and Co ferrite (CoFe 2 O 4 ) grown epitaxially on substrates such as SrTiO 3 or MgO [16,17].…”