Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses

Abstract

Using liquid phase epitaxy (LPE) technique (111) yttrium iron garnet (YIG) films with thicknesses of ≈100 nm and surface roughnesses as low as 0.3 nm have been grown as a basic material for spin-wave propagation experiments in microstructured waveguides. The continuously strained films exhibit nearly perfect crystallinity without significant mosaicity and with effective lattice misfits of ∆a ⊥ /a s ≈ 10 −4 and below. The film/substrate interface is extremely sharp without broad interdiffusion layer formation. All LPE films exhibit a nearly bulk-like saturation magnetization of (1800±20) Gs and an 'easy cone' anisotropy type with extremely small in-plane coercive fields <0.2 Oe. There is a rather weak in-plane magnetic anisotropy with a pronounced six-fold symmetry observed for saturation field <1.5 Oe. No significant out-of-plane anisotropy is observed, but a weak dependence of the effective magnetization on the lattice misfit is detected. The narrowest ferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is the lowest values reported so far for YIG films of 100 nm thicknesses and below. The Gilbert damping coefficient for investigated LPE films is estimated to be close to 1 × 10 −4 .

Magnonic crystals for data processing

“…However, the thickness of these films, which is in the micrometer range, does not allow for the fabrication of YIG structures of nanometer sizes. Therefore, the fabrication of nanostructures became possible only within the last few years with the development of technologies for the growth of highquality nm-thick YIG films (see second column in table 1) by means of, e.g., pulsed-laser deposition [119][120][121][122][123], sputtering [124], or modification of the LPE growth technology [125,126]. Although the quality of these films is still worse than that of micrometer-thick LPE YIG films, it is already good enough to satisfy many requirements of magnonic applications [9].…”

Spin waves with large decay length and few 100 nm wavelengths in thin yttrium iron garnet grown at the wafer scale

“…The extracted decay length l d amounted to 0.86 mm. Small λ, high v g and large l d are key figures of merit when aiming at non-charged based signal transmission and logic devices with spin waves.Thin films of the insulating ferrimagnet yttrium iron garnet (YIG) have recently shown to exhibit small spin-wave (SW) damping [1][2][3][4][5][6][7] . A large decay length of up to 0.58 mm was reported for SWs in a 20 nm thick YIG film 3 .…”

“…To scale substrate sizes up, PLD is however very challenging. Here, for instance, magnetron sputtering 13 and liquid phase epitaxy 7,14 are more suitable. Still, for decades, commercially available YIG films grown by liquid phase epitaxy (LPE) had a thickness of 1 µm and beyond 15 .…”

Parametric Generation of Propagating Spin Waves in Ultrathin Yttrium Iron Garnet Waveguides

“…The investigated system here is a single nano‐YIG WG with a thickness of 85 nm and a width of 1 μm. The nano‐YIG films have been grown on a 500 μm thick gadolinium gallium garnet (GGG) substrate with (111) orientation by liquid phase epitaxy . The WGs were structured by using a metal hard mask technique with electron beam lithography and subsequent Ar+ ion beam etching.…”