Time-resolved electron dynamics in antiferromagnetic CoO(001) thin films

Fuente: arXiv
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Main Authors: Augstein, Mathias, Wührl, Friederike, Gillmeister, Konrad, Chiang, Cheng-Tien, Widdra, Wolf
Format: Preprint
Published: 2025
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author Augstein, Mathias
Wührl, Friederike
Gillmeister, Konrad
Chiang, Cheng-Tien
Widdra, Wolf
author_facet Augstein, Mathias
Wührl, Friederike
Gillmeister, Konrad
Chiang, Cheng-Tien
Widdra, Wolf
contents Ultrathin antiferromagnetic CoO(001)-(1x1) films of 2 and 4 monolayers (ML) on Ag(001) are investigated by time- and angle-resolved two-photon photoelectron (2PPE) spectroscopy. Pump-probe spectra show unoccupied states between 3.6 and 4.0\,eV above the Fermi level ($E_{F}$), which are identified as image potential states with momentum-dependent lifetimes between 12 to 20\,fs. Electrons photoexcited across the band gap show lifetimes of 27\,fs at the bottom of the Co $3d$ $t_{2g}$-derived conduction band minimum. This lifetime is much shorter than in conventional semiconductors. Our observations point either to strong electron correlation effects as has been demonstrated for NiO or to an ultrafast relaxation pathway via metallic substrate states.
format Preprint
id arxiv_https___arxiv_org_abs_2505_10990
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Time-resolved electron dynamics in antiferromagnetic CoO(001) thin films
Augstein, Mathias
Wührl, Friederike
Gillmeister, Konrad
Chiang, Cheng-Tien
Widdra, Wolf
Materials Science
Strongly Correlated Electrons
Ultrathin antiferromagnetic CoO(001)-(1x1) films of 2 and 4 monolayers (ML) on Ag(001) are investigated by time- and angle-resolved two-photon photoelectron (2PPE) spectroscopy. Pump-probe spectra show unoccupied states between 3.6 and 4.0\,eV above the Fermi level ($E_{F}$), which are identified as image potential states with momentum-dependent lifetimes between 12 to 20\,fs. Electrons photoexcited across the band gap show lifetimes of 27\,fs at the bottom of the Co $3d$ $t_{2g}$-derived conduction band minimum. This lifetime is much shorter than in conventional semiconductors. Our observations point either to strong electron correlation effects as has been demonstrated for NiO or to an ultrafast relaxation pathway via metallic substrate states.
title Time-resolved electron dynamics in antiferromagnetic CoO(001) thin films
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2505.10990