Critical anomalous Hall behavior in Pt/Co/Pt trilayers grown on paper with perpendicular magnetic anisotropy

Abstract

Perpendicular magnetic anisotropy was observed in Pt/Co/Pt trilayers prepared on three kinds of paper substrates with conspicuous difference of roughness by sputtering. Anomalous Hall effect exhibits well magnetic transport properties for partial samples. The trends of Hall resistivity over longitudinal resistivity (ρAH/ρxx) versus ρxx are bending instead of a traditional linear relationship for thick single-layer Co films. Further, study reveals that this behavior strongly depends on ratios among contributions from the skew scattering induced by residual resistance and phonons, the side jump and the intrinsic parts in anomalous Hall effect. A 3D map of correlation coefficients (R) of ρAH/ρxx and ρxx shows the ratios locate at a critical and ultra-narrow area for our trilayers. This study may throw new light on the understanding of anomalous Hall effect as well as lead to an economical and practical method to fabricate Hall devices on flexible substrates.

A novel method to evaluate spin diffusion length of Pt

“…( 2) can fit the data perfectly. These results are consistent with our reported data 31,32 . It reveals that the dependence of ρ AH /ρ xx versus ρ xx shows a straighter line at special ratios among a ′ , a ′′ and bρ xx0 only, such as the cases in a bulk material and a thick film.…”

Bending Strain-Tailored Magnetic and Electronic Transport Properties of Reactively Sputtered γ′-Fe4N/Muscovite Epitaxial Heterostructures toward Flexible Spintronics

“…Flexible spintronics combines the conventional spintronics with the advantages of mechanically flexible electronics due to light weight, chemical inertness, thermal conductivity, multifunction, and environmental friendliness. − Lots of flexible magnetic materials have been widely investigated for wearable spintronic devices, such as the giant magnetoresistance sensors, , magnetoelectric devices, , and skin electronics. − Many methods have been used to produce large strains, which can exert significant effects on magnetic properties, such as dual-ion-tuned electronic structures, depositing films on various substrates, and strain-mediated magnetoelectric coupling effects . In flexible spintronics, the magnetic and electronic transport properties of the ferromagnetic films are mainly tailored via applying the bending strains (>1.0%), − which is larger than the piezoelectric strain (<0.2%) in PbZr x Ti 1‑ x O 3 . , However, the integration of epitaxial films on flexible organic substrates is quite difficult due to the lower fabrication temperatures (<300 °C) and lattice mismatch. − Meanwhile, the large strain-induced magnetization and resistance change are also not easy to achieve because most of the ferromagnetic films deposited on flexible substrates are polycrystalline or amorphous. The poor lattice symmetry, low anisotropy, and complicated grain boundaries in the polycrystalline or amorphous films, such as flexible polycrystalline Fe 81 Ga 19 and amorphous Co 40 Fe 40 B 20 films, ,− make them have a weaker response to the strains, which can result in a smaller modulation on the magnetic and electronic transport properties than that in the epitaxial films. , Since, the epitaxial films can effectively transfer the strain from the substrate, the epitaxial ferromagnetic films with a large magnetization, anisotropy magnetoresistance (AMR), and anomalous Hall resistivity are more desirable. − Meanwhile, the muscovite simplified as “mica” [KAl 2 Si 3 AlO 10 )­(OH) 2 ] has been paid much attention to achieve a large strain due to its large stretchability. − The melting point of mica is as high as 1300 °C, which is necessary to fabricate the epitaxial ferromagnetic films. ,,, …”

Bending strain tailored exchange bias in epitaxial NiMn/ γ ′-Fe4N bilayers

“…14,15 However, the growth of epitaxial magnetic films on flexible organic substrates is a challenge due to the low fusing temperature (<300 C) and lattice mismatch. 16,17 Straininduced magnetization and resistance changes are also not easily achieved because most of the ferromagnetic (FM) films grown on flexible substrates are polycrystalline or amorphous. Owing to poor lattice symmetry, low anisotropy, and grain boundaries in polycrystalline or amorphous films, 11,18 the strain effects on the magnetic and electronic transport properties are smaller than those in epitaxial films because the epitaxial films can effectively transfer the strain from substrates.…”