Impact of magnetic moment and anisotropy of Co$_\textrm{1-x}$Fe$_\textrm{x}$ thin films on the magnetic proximity effect of Pt

TL;DR

This study investigates how the magnetic moment and anisotropy of Co-Fe thin films influence the magnetic proximity effect in adjacent Pt layers, revealing a linear relationship between Pt and ferromagnet moments and anisotropy transfer.

Contribution

It provides the first systematic analysis of the dependence of Pt's induced magnetic moment and anisotropy on different Co-Fe alloy compositions and orientations.

Findings

Maximum Pt magnetic moment observed in Pt/Co33Fe67 bilayer.

Linear correlation between Pt moment and ferromagnet magnetization.

Pt adopts the magnetic anisotropy of the underlying ferromagnet.

Abstract

We present a systematic study of the magnetic proximity effect in Pt, depending on the magnetic moment and anisotropy of adjacent metallic ferromagnets. Element-selective x-ray resonant magnetic reflectivity measurements at the Pt absorption edge (11565$\,$eV) are carried out to investigate the spin polarization of Pt in Pt/Co$_\textrm{1-x}$Fe$_\textrm{x}$ bilayers. We observe the largest magnetic moment of (0.72$\,\pm\,$0.03)$\, \mu_\textrm{B}$ per spin polarized Pt atom in Pt/Co$_\textrm{33}$Fe$_\textrm{67}$, following the Slater-Pauling curve of magnetic moments in Co-Fe alloys. In general, a clear linear dependence is observed between the Pt moment and the moment of the adjacent ferromagnet. Further, we study the magnetic anisotropy of the magnetized Pt which clearly adopts the magnetic anisotropy of the ferromagnet below. This is depicted for Pt on Fe(001) and on Co$_\textrm{50}$Fe$_\textrm{50}$(001), which have a 45$^{\circ}$ relative rotation of the fourfold magnetocrystalline anisotropy.