arXiv subjects

T. Gouder

Publications and source records attributed to T. Gouder.

4 recordsLinked to original sources

arXiv2026

Photoelectron Spectroscopy Study of U-Te Thin Films: A Unified Perspective of Hybridization Effects across Compositions

Uranium tellurides span magnetic and superconducting ground states, yet systematic electronic-structure information across the U-Te series remains scarce. In this study, we perform photoemission measurements on freshly prepared UxTey thin films covering the range of bulk stoichiometries under ultra-high vacuum (10^-9 Pa), enabling clean surfaces and compositions matching bulk phases, including the celebrated UTe2. X-ray and ultraviolet photoelectron spectroscopy (XPS/UPS) reveal consistent evolution of the U 4f and Te 3d core levels and valence states across the series, in good agreement with the limited bulk data. Supported by uniform ab initio calculations for all U-Te compounds, we identify systematic trends in U-Te hybridization and charge-transfer effects across the series. These results establish thin-film photoemission as a reliable route for mapping electronic-structure trends in tellurides of heavy elements with diverse electronic ground states.

cond-mat.mtrl-sci↗

arXiv2023

Strain-driven switching between antiferromagnetic states in frustrated antiferromagnet UO2 probed by exchange bias effect

Frustrated antiferromagnets offer a captivating platform to study the intricate relationship of magnetic interactions, geometric constraints, and emergent phenomena. By controlling spin orientations, these materials can be tailored for applications in spintronics and quantum information processing. The research focuses on the interplay of magnetic and exchange anisotropy effects in artificial heterostructures based on a canonical frustrated antiferromagnet, UO2. The potential to manipulate the spin directions in this material and switch between distinct antiferromagnetic states is investigated using substrate-induced strain. The phenomenon is probed using exchange bias (EB) effects in stoichiometric UO2/Fe3O4 bilayers. By employing many-body first-principles calculations magnetic configurations in the UO2 layers are identified. Even a minor tetragonal distortion triggers a transition between antiferromagnetic states of different symmetries, driven by a robust alteration of single-ion anisotropy due to the distortion. Consequently, this change influences the arrangement of magnetic moments at the UO2/Fe3O4 interface, affecting the magnitude of exchange bias. The findings showcase how epitaxial strain can effectively manipulate the antiferromagnetic states in frustrated antiferromagnets by controlling single-site anisotropy.

cond-mat.mtrl-sci↗

arXiv2013

Non-magnetic ground state of PuO$_2$

The correlated band theory implemented as a combination of the local density approximation with the exact diagonalization of the Anderson impurity model is applied to PuO$_2$. We obtain an insulating electronic structure consistent with the experimental photoemission spectra. The calculations yield the band gap of 1.8 eV and a non-magnetic singlet ground state that is characterized by a non-integer filling of the plutonium $f$ shell ($n_f\approx 4.5$). Due to sizeable hybridization of the $f$ shell with the $p$ states of oxygen, the ground state is more complex than the four-electron Russell--Saunders ${}^5{\rm I}_4$ manifold split by the crystal field. The inclusion of hybridization improves the agreement between the theory and experiment for the magnetic susceptibility.

cond-mat.mtrl-sci↗

arXiv2005

Nature of non-magnetic strongly-correlated state in delta-plutonium

Ab-initio relativistic dynamical mean-field theory is applied to resolve the long-standing controversy between theory and experiment in the "simple" face-centered cubic phase of plutonium called delta-Pu. In agreement with experiment, neither static nor dynamical magnetic moments are predicted. In addition, the quasiparticle density of states reproduces not only the peak close to the Fermi level, which explains the large coefficient of electronic specific heat, but also main 5f features observed in photoelectron spectroscopy.

cond-mat.str-el↗