Perpendicular magnetic anisotropy and spin mixing conductance in polycrystalline europium iron garnet thin films

Abstract

Polycrystalline single-phase europium iron garnet films (EuIG, Eu3Fe5O12, a ferrimagnetic insulator), with thicknesses from 25 to 50 nm and roughness <1 nm, have been grown on various substrates using pulsed laser deposition followed by a rapid thermal anneal. The films are under strain that originates primarily from thermal mismatch and leads to a magnetoelastic anisotropy that dominates the net anisotropy. EuIG grown on quartz (0001) demonstrated perpendicular magnetic anisotropy (PMA) attributed to the in-plane (IP) compressive thermal mismatch strain, whereas films on (11 2¯ 0) quartz, Si, fused silica, and yttria-stabilized zirconia exhibited an IP easy axis due to tensile strain, consistent with the positive magnetostriction of polycrystalline EuIG. For the PMA EuIG, the saturation magnetization was close to that of bulk EuIG, and the out-of-plane coercivity ranged from 600 to 900 Oe, depending on the film thickness. Spin transport measurements on Pt/EuIG/quartz heterostructures gave an anomalous Hall effect-like spin Hall magnetoresistance similar to that of Pt/epitaxial single crystal EuIG. These results show that high quality polycrystalline garnets can be grown with PMA making them useful for applications in spintronic devices.

Dysprosium Iron Garnet Thin Films with Perpendicular Magnetic Anisotropy on Silicon

“…The amplitude of the AHE loop (11.0 × 10 −4 µΩ cm) is close in magnitude to that measured for other garnet/Pt heterostructures including EuIG, TbIG, and TmIG. [2,19,23] The IP SMR loop could not be completely saturated in our experimental setup. However, a fit to a macrospin model produced an anisotropy field of 1.2 T and an IP SMR amplitude of 42.4 × 10 −4 µΩ cm with a good fit to the experimental data.…”

“…Films annealed at 750 °C had grain sizes on the order of ≈100 nm (obtained from the XRD peak width), comparable to EuIG/ quartz films. [23] For films of roughly 40 nm thickness, large grains were obtained for temperatures above 850 °C, but there was little dependence of grain size on temperature in the range of 850-950 °C.…”

“…[9][10][11] Selection of the rare-earth ion enables tuning of the saturation www.advelectronicmat.de temperature used to crystallize the films after growth. [20,23,37] Considerable work was done on thin film polycrystalline REIGs for bubble memory in the 1960-1970s, where PMA was promoted by lowering the magnetization and therefore the shape anisotropy (e.g., by Al or Ga substitution for Fe), and from a growth-induced anisotropy. [38,39] Recently PMA was achieved in polycrystalline films of europium iron garnet (EuIG) on (0001) quartz, [23] Dy 3−x Bi x Fe 5−y Ga y O 12 on glass, [40] and for Dy 3−x Ce x Fe 5−y Al y O 12 on Si [41] due to a dominant magnetoelastic anisotropy.…”

“…Thin films of the archetypical yttrium iron garnet (Y 3 Fe 5 O 12 ,YIG) and rare‐earth iron garnets (RE 3 Fe 5 O 12 , REIG) have attracted considerable attention recently for studies of spin torques, spin waves, and magneto‐optical effects . Selection of the rare‐earth ion enables tuning of the saturation magnetization, magnetocrystalline anisotropy, magnetostriction, Gilbert damping parameter, and magnetooptical spectral response, and the net anisotropy may be varied widely by choice of substrate, which affects the strain state of the film . Ferrimagnetic insulators, such as YIG and REIG, are particularly promising for spintronics as they do not contribute Ohmic losses from parasitic current shunting and exhibit fast magnetization dynamics and low losses in the THz regime .…”

Interfacial and Bulk Magnetic Properties of Stoichiometric Cerium Doped Terbium Iron Garnet Polycrystalline Thin Films

“…The effective anisotropy from magnetometry was obtained from the difference in the area under the anhysteretic M – H curves for the in‐plane and out‐of‐plane geometries. [ 52 ]…”