Bandwidth-control orbital-selective delocalization of 4f electrons in epitaxial Ce films.
Nat Commun 2021;
12:2520. [PMID:
33947850 PMCID:
PMC8096960 DOI:
10.1038/s41467-021-22710-2]
[Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 03/19/2021] [Indexed: 11/09/2022] Open
Abstract
The 4f-electron delocalization plays a key role in the low-temperature properties of rare-earth metals and intermetallics, and it is normally realized by the Kondo coupling between 4f and conduction electrons. Due to the large Coulomb repulsion of 4f electrons, the bandwidth-control Mott-type delocalization, commonly observed in d-electron systems, is difficult in 4f-electron systems and remains elusive in spectroscopic experiments. Here we demonstrate that the bandwidth-control orbital-selective delocalization of 4f electrons can be realized in epitaxial Ce films by thermal annealing, which results in a metastable surface phase with reduced layer spacing. The quasiparticle bands exhibit large dispersion with exclusive 4f character near [Formula: see text] and extend reasonably far below the Fermi energy, which can be explained from the Mott physics. The experimental quasiparticle dispersion agrees well with density-functional theory calculation and also exhibits unusual temperature dependence, which could arise from the delicate interplay between the bandwidth-control Mott physics and the coexisting Kondo hybridization. Our work opens up the opportunity to study the interaction between two well-known localization-delocalization mechanisms in correlation physics, i.e., Kondo vs Mott, which can be important for a fundamental understanding of 4f-electron systems.
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