Stress-induced magnetic properties of PLD-grown high-quality ultrathin YIG films

Abstract

Yttrium iron garnet (YIG:Y3Fe5O12) thin films were grown on (111) gadolinium gallium garnet (Gd3Ga5O12, GGG) substrates using pulsed-laser deposition under several different deposition and annealing conditions. X-ray diffraction measurements revealed that the crystallographical orientation of the YIG films is pseudomorphic to and the same as that of the GGG substrate, with a slight rhombohedral distortion along the surface normal. Furthermore, X-ray reciprocal space mapping evidenced that in-situ annealed YIG films during film growth are under compressive strain, whereas ex-situ annealed films have two different regions under compressive and tensile strain. The saturation magnetization (4πMS) of the films was found to vary, according to the deposition conditions, within the range of 1350 to 1740 G, with a very low coercivity of HC < 5 Oe. From ferromagnetic resonance (FMR) measurements, we estimated the effective saturation magnetization (4πMeff) to be 1810 to 2530 G, which are larger than that of single crystalline bulk YIG (∼1750 G). Such high values of 4πMeff are attributable to the negative anisotropy field (HU) that increases in size with increasing compressive in-plane strain induced in YIG films. The damping constant (αG) of the grown YIG films was found to be quite sensitive to the strain employed. The lowest value of αG obtained was 2.8 × 10−4 for the case of negligible strain. These results suggest a means of tailoring HU and αG in the grown YIG films by the engineering of strain for applications in spintronics and magneto-optical devices.

Interplay of Magnetization Dynamics with a Microwave Waveguide at Cryogenic Temperatures

“…5 provides approximately the same strain ≈ +5.6×10 −4 at the interface with unrelaxed Nb, and a larger opposite-sign strain ≈ −4 × 10 −4 at the interface with the room-T deposited or relaxed Nb. These values are well comparable with the growth induced tensions provided by the lattice misfit between the GGG substrate and the YIG film that induces the uniaxial anisotropy in LPE-grown 28 and PLD-grown 49,50 films.…”

Ferromagnetic resonance studies of strain tuned Bi:YIG films

“…6 (d)) to see the correlation between the precessional damping and magnetic anisotropy. In our BiYIG thin film system, we observe a nonlinear relationship between α and H u , similar to YIG and can be attributed to spin wave damping induced by increment in strain [64]. Rhombohedral distortion arising due to lattice mismatch between the film and the substrate leads to change in magnetic properties through spin orbit coupling [3].…”

Preferred‐oriented polycrystalline Y3Fe5O12 films grown on quartz with low microwave loss

“…The fitting parameters gave the values of as 33 Oe and as 16 × 10 −3 . Although the “” of this preferred (100)‐oriented polycrystalline YIG films are larger than that of high‐quality epitaxial YIG films, 6,20 they are still much smaller than some of the results reported in recent years; 1.2 × 10 −1 , 14 21 × 10 −3 , 21 and 27 × 10 −3 22 . These parameters would be further reduced if the films can be fabricated into a fully oriented or textured form.…”

“…The magnetic relaxation is often characterized by the Gilbert damping constant, which is strongly affected by the structural properties and quality of the film 2,6 . Damping factors can be estimated according to 20 aswhere α is the intrinsic Gilbert damping parameter and is a long‐range inhomogeneity‐caused line broadening, which is extrinsic and depends on the film quality 1,2 .…”

“…Recent developments in spintronics, magnonics, caloritronics, and metamaterials based on YIG have further stimulated intensive studies to grow the YIG films with low ferromagnetic resonance linewidth (FMR ~ 1 Oe) and saturation magnetization () close to YIG single‐crystal value (1750 G) 3‐5 . Normally, high‐quality epitaxial YIG film deposition always requires structurally similar with very small lattice mismatch (0.06%) gadolinium gallium garnet (GGG) substrate 6 . However, manufacturing cost and incompatibility with current semiconductor technology often precludes their widespread application.…”