Ab initio study of 2p-core level x-ray photoemission spectra in ferromagnetic transition metals

TL;DR

This study uses an ab initio method to analyze 2p-core level x-ray photoemission spectra in ferromagnetic transition metals, revealing element- and spin-dependent spectral features and magnetic threshold energy behavior.

Contribution

It introduces a computational approach to accurately reproduce and interpret core-level spectra in ferromagnetic metals, linking spectral shapes to electron screening effects.

Findings

Spectra match experimental observations well.

Spectral shapes depend on element and spin.

Magnetic threshold energy decreases from Fe to Ni.

Abstract

We study the 2p-core level x-ray photoemission spectra in ferromagnetic transition metals, Fe, Co, and Ni using a recently developed ab initio method.The excited final states are set up by distributing electrons on the one-electron states calculated under the fully screened potential in the presence of the core hole. We evaluate the overlap between these excited states and the ground state by using one-electron wave functions, and obtain the spectral curves as a function of binding energy. The calculated spectra reproduce well the observed spectra displaying interesting dependence on the element and on the spin of the removed core electron. The origin of the spectral shapes is elucidated in terms of the one-electron states screening the core hole. The magnetic splitting of the threshold energy is also estimated by using the coherent potential approximation within the fully screened potential approximation. It decreases more rapidly than the local spin moment with moving from Fe to Ni. It is estimated to be almost zero for Ni despite the definite local moment about 0.6\mu_B, in agreement with the experiment.