The role of electron confinement in Pd films for the oscillatory magnetic anisotropy in an adjacent Co layer

TL;DR

This study investigates how quantum well states in Pd films influence the magnetic anisotropy in an adjacent Co layer, revealing a periodic variation linked to Pd thickness and suggesting new ways to tailor magnetic properties.

Contribution

It demonstrates the direct correlation between quantum well states in Pd and the oscillatory magnetic anisotropy in Co, providing experimental evidence and analysis of this phenomenon.

Findings

Quantum well states in Pd cross the Fermi level periodically with Pd thickness.

Magnetic anisotropy in Co varies periodically with Pd thickness, with a 6-layer period.

QWS in Pd influence the magnetic anisotropy of the Co layer.

Abstract

We demonstrate the interplay between quantum well states in Pd and the magnetic anisotropy in Pd/Co/Cu(001) by combined scanning tunneling spectroscopy (STS) and magneto optical Kerr effect (MOKE) measurements. Low temperature scanning tunneling spectroscopy reveals occupied and unoccupied quantum well states (QWS) in atomically flat Pd films on Co/Cu(001). These states give rise to sharp peaks in the differential conductance spectra. A quantitative analysis of the spectra reveals the electronic dispersion of the Pd(001) d-band ($\Delta$$_5$-type) along the $\Gamma$-X direction. \textit{In-situ} MOKE experiments on Pd/Co/Cu(1, 1, 13) uncover a periodic variation of the in-plane uniaxial magnetic anisotropy as a function of Pd thickness with a period of 6 atomic layers Pd. STS shows that QWS in Pd cross the Fermi level with the same periodicity of 6 atomic layers. Backed by previous theoretical work we ascribe the variation of the magnetic anisotropy in Co to QWS in the Pd overlayer. Our results suggest a novel venue towards tailoring uniaxial magnetic anisotropy of ferromagnetic films by exploiting QWS in an adjacent material with large spin-orbit coupling.