Ion Redistribution and Lattice-Distortion-Modulated d-Electron Correlation in Layered Multiferroic ABP₂S₆ Probed by X-ray Photoelectron Spectroscopy

@misc{tang2026redistribution,
  title = {{Ion Redistribution and Lattice-Distortion-Modulated d-Electron Correlation in Layered Multiferroic ABP$_2$S$_6$ Probed by X-ray Photoelectron Spectroscopy}},
  author = {Jing Tang and Ruiqi Lu and J. Anibal Boscoboinik and Xi Ling},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.08728},
  eprint = {2611.08728},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.08728},
}

TY  - UNPB
TI  - Ion Redistribution and Lattice-Distortion-Modulated d-Electron Correlation in Layered Multiferroic ABP_2S_6 Probed by X-ray Photoelectron Spectroscopy
AU  - Jing Tang
AU  - Ruiqi Lu
AU  - J. Anibal Boscoboinik
AU  - Xi Ling
PY  - 2026
DA  - 2026/11/05
PB  - arXiv
DO  - 10.48550/arxiv.2611.08728
UR  - https://arxiv.org/abs/2611.08728
AB  - Ferroelectric phase transitions are driven by ion displacement-induced symmetry breaking, yet their chemical signatures are rarely probed directly at the atomic level. Here, we establish temperature-dependent X-ray photoelectron spectroscopy (XPS) as a powerful and quantitative probe of ferroelectric phase transitions by tracking ion migration-induced changes in local chemical environments. Using van der Waals (vdW) layered ABP_2S_6 materials as a model system, we systematically compare CuCrP_2S_6 (CCPS), which undergoes a ferroelectric phase transition, with AgCrP_2S_6 (ACPS), which remains paraelectric over the same temperature range. While ACPS exhibits only smooth trivial thermal broadening and shifts in core-level spectra, CCPS shows pronounced and enormously large temperature-dependent XPS anomalies across the ferroelectric transition, demonstrating that XPS is intrinsically sensitive to ferroelectric order. Detailed analysis of the Cu 2p spectra reveals that these anomalies originate from temperature-driven Cu^+ ion migration associated with polarization switching, whereas concurrent changes in the Cr core levels reflect secondary lattice squeezing and modulation of d-electron correlation induced by Cu displacement. Supported by a ferroelectric structural model, we further correlate XPS binding-energy shifts with the magnitude of Cu-ion migration, enabling a quantitative estimation of ionic displacement directly from spectroscopic observables. This work also highlights the rich information provided by temperature-dependent XPS for detecting and quantifying ferroelectric phase transitions and ion migration, offering a general chemical probe for ferroic materials and ion-displacement-driven phase transitions.
ER  -