Quantized electronic fine structure with large anisotropy in ferromagnetic Fe films

TL;DR

This study observes quantized electronic fine structures in thin ferromagnetic Fe films with large anisotropy, revealing direction-dependent band dispersion and spin characteristics through spectroscopy and theoretical calculations.

Contribution

It provides the first spectroscopic evidence of anisotropic quantum well states in Fe films and links the anisotropy to film thickness and substrate coupling.

Findings

Quantum well states detected down to 10 meV binding energy.

Pronounced anisotropy in band dispersion within the surface plane.

States exhibit both majority and minority spin character.

Abstract

We report on the spectroscopic observation of a quantized electronic fine structure near the Fermi energy in thin Fe films grown on W(110). The quantum well states are detected down to binding energies of $\sim$10 meV by angle-resolved photoelectron spectroscopy. The band dispersion of these states is found to feature a pronounced anisotropy within the surface plane: It is free-electron like along the $\bar{\Gamma \rm{H}}$-direction while it becomes heavy along $\bar{\Gamma \rm{N}}$. Density functional theory calculations identify the observed states to have both majority and minority spin character and indicate that the large anisotropy can be dependent on the number of Fe-layers and coupling to the substrate.