Large-Pore Mesoporous Ho₃Fe₅O₁₂ Thin Films with a Strong Room-Temperature Perpendicular Magnetic Anisotropy by Sol–Gel Processing

Abstract

We report the evaporation-induced self-assembly synthesis of large-pore mesoporous thin films of ferrimagnetic holmium iron garnet (Ho 3 Fe 5 O 12 ) from nitrate salt precursors and a polyisobutylene-block-poly(ethylene oxide) polymer structure-directing agent. The phase composition, atomic bonding configuration, and pore structure at the top surface and in the interior of the films were investigated by microscopy, scattering, and spectroscopy techniques, including synchrotron-based grazing incidence small-angle X-ray scattering, X-ray photoelectron spectroscopy, X-ray diffraction (including Rietveld refinement), and others. The data provide evidence that the sol-gel derived material is single phase garnet with 27 nm diameter crystallites and few defects after heating to 850 °C in air and the continuous network of pores averaging 23 nm in diameter is preserved to a large extent, despite a solid-solid conversion from metastable h- KeywordsRare-earth iron garnet, magnetic anisotropy, out-of-plane easy axis, sol-gel chemistry, selfassembly 3

CoFe2O4 and CoFe2O4‐SiO2 Nanoparticle Thin Films with Perpendicular Magnetic Anisotropy for Magnetic and Magneto‐Optical Applications

“…Although these stresses are expected to relax after a certain fi lm thickness, it was reported that they indeed can produce strain-induced magnetic anisotropy in porous magnetic thin fi lm nanostructures of similar thicknesses. [ 30,46 ] Therefore, we believe that in our system, strain-induced anisotropy as a result of the constrained sintering conditions is the most likely source of the observed perpendicular magnetic anisotropy. Inplane tensile stresses create an out of plane easy magnetization axis perpendicular to the substrate considering the negative magnetostriction of CoFe 2 O 4 .…”

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

“…[9] In epitaxial films, magnetoelastic anisotropy can be tuned via the lattice mismatch with the substrate. PMA has also been obtained in several single-layer rare-earth-substituted garnet films as a result of magnetoelastic anisotropy, [24][25][26][27] but the substitution of rare earth ions for Y in the iron garnet system tends to increase the Gilbert damping. 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.…”

Applying Capacitive Energy Storage for In Situ Manipulation of Magnetization in Ordered Mesoporous Perovskite-Type LSMO Thin Films

“…It should be noted, nevertheless, that they were determined from very small volumes (≈2.1 × 10 −15 cm 3 ), and therefore should be treated as estimates only; yet, they are consistent with those found for other large-pore mesoporous metal oxide thin films prepared using the same polymer structure-directing agent. 49,50 Results from topological analysis of the pore space using the skeletonization approach. (d) 2D slice through the reconstructed pore space.…”