Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

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

E. A. Tereshina-Chitrova, S. G. Alex, O. Koloskova, L. Havela, L. Horak, O. Romanyuk, F. Huber, T. Gouder, M. Divis

TL;DR

This work addresses how U–Te hybridization evolves across the uranium telluride series by combining in situ photoelectron spectroscopy on clean, composition-tuned thin films with uniform first-principles calculations. The authors synthesize 10–30 nm U–Te films under ultra-high vacuum with controlled Te:U ratios, perform XPS and UPS to track core-level shifts, line shapes, and valence-band signatures, and compare with FPLO and (L)APW+lo LSDA calculations to quantify charge-transfer and occupancy trends. They observe systematic core-level broadening, binding-energy shifts, and evolving 5f/6d/Te 5p character across the series, including UTe2’s intermediate-valence behavior, which is corroborated by the calculations showing a reduced U-5f occupation with higher Te content. Overall, the study demonstrates that thin-film photoemission provides a robust route to map electronic-structure trends in heavy-element chalcogenides and links surface spectroscopy to bulk-like electronic ground states.

Abstract

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.

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

TL;DR

This work addresses how U–Te hybridization evolves across the uranium telluride series by combining in situ photoelectron spectroscopy on clean, composition-tuned thin films with uniform first-principles calculations. The authors synthesize 10–30 nm U–Te films under ultra-high vacuum with controlled Te:U ratios, perform XPS and UPS to track core-level shifts, line shapes, and valence-band signatures, and compare with FPLO and (L)APW+lo LSDA calculations to quantify charge-transfer and occupancy trends. They observe systematic core-level broadening, binding-energy shifts, and evolving 5f/6d/Te 5p character across the series, including UTe2’s intermediate-valence behavior, which is corroborated by the calculations showing a reduced U-5f occupation with higher Te content. Overall, the study demonstrates that thin-film photoemission provides a robust route to map electronic-structure trends in heavy-element chalcogenides and links surface spectroscopy to bulk-like electronic ground states.

Abstract

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.
Paper Structure (11 sections, 11 figures)

This paper contains 11 sections, 11 figures.

Table of Contents

  1. Introduction
  2. Materials and methods
  3. Samples synthesis
  4. Spectroscopy methods
  5. Computational methods
  6. Experimental results
  7. X-ray Photoelectron Spectroscopy Study
  8. Ultraviolet Photoelectron Spectroscopy Study
  9. Calculations and discussion
  10. Conclusions
  11. Supplementary figures

Figures (11)

  • Figure 1: (Left) U-4f core-level spectra of U-Te thin films, measured for varying Te:U ratios, display the 4f$_{7/2}$ and 4f$_{5/2}$ peaks, separated by 11 eV due to spin-orbit interaction. (Right) For Te, the evolution of the dominant core-level line Te-3d$_{5/2}$ normalized to the maximum of its intensity is shown for various Te:U concentrations (the Te-3d$_{3/2}$ line is located at approx. 583 eV).
  • Figure 2: Binding energy shifts for the dominant U-4f$_{7/2}$ and Te-3d$_{5/2}$ core-level lines as compared to $\alpha$-U (the reference position is at 377.3±0.1 eV) and pure Te (the reference position is at 573.1±0.1 eV) in U-Te films. The size of the data points includes the estimated experimental error.
  • Figure 3: Normalized He II UPS spectra for the initial $\alpha$-U film compared with various U-Te composition films. For the UTe$_2$ thin film, we also show the XPS data, scaled to match the UPS data. Vertical solid line marks the Fermi energy $E_{\mathrm{F}}$ = 0, while broken vertical lines serve as visual guides.
  • Figure 4: Comparison of He II with He I UPS spectra for selected U-Te films compositions.
  • Figure 5: The evolution of the U-6p$_{3/2}$ emission across various U-Te compositions. The U6p$_{1/2}$ is located at higher binding energies (25-27 eV).
  • ...and 6 more figures