The Spin-Polarization of the Split Kondo State

TL;DR

This study uses spin-resolved scanning tunneling microscopy to measure the spin polarization of the magnetic field-split Kondo state, revealing full spin polarization with peaks below and above the Fermi energy.

Contribution

It introduces a quantitative method to determine spin polarization of the split Kondo state using a simple model and spin Hamiltonian analysis.

Findings

Kondo peaks are fully spin-polarized.

Peak width and height scale with Zeeman energy.

Majority and minority spins are below and above Fermi energy.

Abstract

Spin-resolved scanning tunneling microscopy is employed to quantitatively determine the spin-polarization of the magnetic field-split Kondo state. Tunneling conductance spectra of a Kondo-screened magnetic atom are evaluated within a simple model taking into account inelastic tunneling due to spin excitations and two Kondo peaks positioned symmetrically around the Fermi energy. We fit the spin state of the Kondo-screened atom with a Spin Hamiltonian independent of the Kondo effect and account for Zeeman-splitting of the Kondo peak in the magnetic field. We find that the width and the height of the Kondo peaks scales with the Zeeman energy. Our observations are consistent with full spin-polarization of the Kondo peaks, i.e., a majority spin peak below the Fermi energy and a minority spin peak above.