TY - JOUR
T1 - Ultrafast electron localization in the EuNi2(Si0.21Ge0.79)2 correlated metal
AU - Mardegan, Jose R.L.
AU - Zerdane, Serhane
AU - Mancini, Giulia
AU - Esposito, Vincent
AU - Rouxel, Jérémy R.
AU - Mankowsky, Roman
AU - Svetina, Cristian
AU - Gurung, Namrata
AU - Parchenko, Sergii
AU - Porer, Michael
AU - Burganov, Bulat
AU - Deng, Yunpei
AU - Beaud, Paul
AU - Ingold, Gerhard
AU - Pedrini, Bill
AU - Arrell, Christopher
AU - Erny, Christian
AU - Dax, Andreas
AU - Lemke, Henrik
AU - Decker, Martin
AU - Ortiz, Nazaret
AU - Milne, Chris
AU - Smolentsev, Grigory
AU - Maurel, Laura
AU - Johnson, Steven L.
AU - Mitsuda, Akihiro
AU - Wada, Hirofumi
AU - Yokoyama, Yuichi
AU - Wadati, Hiroki
AU - Staub, Urs
N1 - Publisher Copyright:
© 2021 authors. Published by the American Physical Society.
PY - 2021/9
Y1 - 2021/9
N2 - Ultrafast electron delocalization induced by a femtosecond laser pulse is a well-known process in which electrons are ejected from the ions within the laser pulse duration. However, very little is known about the speed of electron localization out of an electron gas in correlated metals, i.e., the capture of an electron by an ion. Here, we demonstrate by means of pump-probe x-ray techniques across the Eu L3 absorption edge that an electron localization process in the EuNi2(Si0.21Ge0.79)2 intermetallic material occurs within a few hundred femtoseconds after the optical excitation. Spectroscopy and diffraction data collected simultaneously at low temperature and for various laser fluences show that the localization dynamics process is much faster than the thermal expansion of the unit cell along the c direction which occurs within picoseconds. Nevertheless, this latter process is still much slower than pure electronic effects, such as screening, and the subpicosecond timescale indicates an optical phonon driven origin. In addition, comparing the laser fluence dependence of the electronic response with that found in other intermediate 4f valence materials, we suggest that the electron localization process observed in this Eu-based correlated metal is mainly related to changes in the 4f hybridization. The observed ultrafast electron localization process sparks fundamental questions for our understanding of electron correlations and their coupling to the lattice.
AB - Ultrafast electron delocalization induced by a femtosecond laser pulse is a well-known process in which electrons are ejected from the ions within the laser pulse duration. However, very little is known about the speed of electron localization out of an electron gas in correlated metals, i.e., the capture of an electron by an ion. Here, we demonstrate by means of pump-probe x-ray techniques across the Eu L3 absorption edge that an electron localization process in the EuNi2(Si0.21Ge0.79)2 intermetallic material occurs within a few hundred femtoseconds after the optical excitation. Spectroscopy and diffraction data collected simultaneously at low temperature and for various laser fluences show that the localization dynamics process is much faster than the thermal expansion of the unit cell along the c direction which occurs within picoseconds. Nevertheless, this latter process is still much slower than pure electronic effects, such as screening, and the subpicosecond timescale indicates an optical phonon driven origin. In addition, comparing the laser fluence dependence of the electronic response with that found in other intermediate 4f valence materials, we suggest that the electron localization process observed in this Eu-based correlated metal is mainly related to changes in the 4f hybridization. The observed ultrafast electron localization process sparks fundamental questions for our understanding of electron correlations and their coupling to the lattice.
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U2 - 10.1103/PhysRevResearch.3.033211
DO - 10.1103/PhysRevResearch.3.033211
M3 - Article
AN - SCOPUS:85115892119
VL - 3
JO - Physical Review Research
JF - Physical Review Research
SN - 2643-1564
IS - 3
M1 - 033211
ER -