Impact of the magnetic proximity effect in Pt on the total magnetic moment of Pt/Co/Ta trilayers studied by x-ray resonant magnetic reflectivity

Abstract

In this work, we study the influence of the magnetic proximity effect (MPE) in Pt on the total magnetic moment of thin film trilayer systems consisting of the ferromagnet (FM) Co adjacent to the heavy metals (HMs) Pt and Ta. We investigate the trilayer systems HM 1 /FM/HM 2 with different stacking order as well as a reference bilayer without any MPE. X-ray resonant magnetic reflectivity (XRMR) is a powerful tool to probe induced magnetism, especially when buried at interfaces in a multilayer. By using XRMR, we are able to obtain magnetic depth profiles of the structural, optical and magnetic parameters. By fitting the experimental data with a Gaussian-like magnetooptic profile taking the structural roughness at the interface into account, we can extract the magnetic moment of the spin-polarized layer. Comparing the obtained moments to the measured total moment of the sample, we can determine the impact of the MPE on the total magnetic moment of the system. Such information can be critical for analyzing spin transport experiments, including spin-orbit torque and spin Hall angle measurements, where the saturation magnetization M s has to be taken into account. Therefore, by combining magnetization measurements and XRMR methods we were able to get a complete picture of the magnetic moment distribution in these trilayer systems containing spin-polarized Pt.

Static magnetic proximity effects and spin Hall magnetoresistance in Pt/Y3Fe5O12 and inverted Geprägs1, Klewe2, Meyer3 et al. 2020Phys. Rev. BSelf Cite12040View full textAdd to dashboardCite

“…One reason could be the poorer fit quality of the asymmetry ratio for the inverted YIG/Pt//YAG bilayer compared to metallic bilayers. Still, the fit result presented here reflects a clear overall global minimum as tested by goodnessof-fit space mappings which have proven effective in previous XRMR studies [89,90]. In addition, the origin of the oscillating background observed for the inverted YIG/Pt//YAG bilayer is unknown and has not been observed previously for metallic bilayers but could affect the quantitative XRMR results as well.…”

Switching of a Magnet by Spin‐Orbit Torque from a Topological Dirac Semimetal

“…First, it has a long spin diffusion length (≈700 nm) and a small spin Hall angle (0.0068) [ 40 ] and can therefore enable efficient transfer of spin from the α‐Sn film to the CoFeB film. Second, the proximity‐induced magnetic moment in Ag is only 0.0136μ B per atom, [ 41 ] or smaller, [ 42 ] one order of magnitude below that of Pt (0.42μ B ) [ 43 ] or Pd (0.41μ B ). [ 44 ] If the moment induced in Ag is large, it could modify or suppress the TSS in the α‐Sn film.…”

Quantitative comparison of the magnetic proximity effect in Pt detected by XRMR and XMCD

“…Furthermore, the influence of the MPE on spin-orbit torque (SOT) efficiencies is still under debate. [9][10][11] Peterson et al 9 report an increase in the field-like SOT by nearly a factor of 4 at 20 K, which is attributed to an increased magnetoresistance caused by the MPE at low temperatures. Contrarily, Zhu et al 10 claim the negligible influence of the MPE on SOT efficiencies, whereas an enhancement of the MPE due to annealing was found.…”