Coupled structural and electronic evolution under pressure in CuIr2Se4, CuRh2S4, and CuRh2Se4

Abstract

Spinel chalcogenides provide a platform for investigating the interplay among metallic, superconducting, and pressure-induced insulating states. Here, we combine synchrotron powder X-ray diffraction and electrical-resistivity measurements to investigate the pressure evolution of CuIr2Se4, CuRh2S4, and CuRh2Se4 over pressure ranges extending beyond those previously explored. High-pressure diffraction reveals closely related monoclinic supercells in all three compounds. For CuIr2Se4 and CuRh2S4, constrained profile fits based on structural models relaxed using density functional theory are compatible with Phase-IV-type bond-disproportionated structures, whereas the data for CuRh2Se4 establish a compatible monoclinic unit cell without resolving its atomic-scale ordering pattern. Insulating-like transport develops abruptly over a narrow pressure range in CuIr2Se4 but more gradually over broader pressure ranges in the Rh-based compounds, in close correspondence with their respective structural transformations. We also establish previously unreported bulk superconductivity in CuIr2Se4 at ambient pressure: zero resistance is attained at 0.29 K, and the accompanying ac diamagnetic response is consistent with nearly complete superconducting shielding. These results establish a close relationship between the formation of the high-pressure monoclinic phases and the evolution toward insulating transport, and demonstrate that transition-metal and chalcogen substitutions tune the characteristic pressure scales and the competition with superconductivity within a closely related structural framework.

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BibTeX RIS

BibTeX

@misc{emi2026coupled,
  title = {{Coupled structural and electronic evolution under pressure in CuIr2Se4, CuRh2S4, and CuRh2Se4}},
  author = {M. Emi and M. Shiomi and K. Kojima and K. Sugimoto and T. Karasawa and H. Suzuki and M. Takahashi and K. Oka and H. Kadobayashi and S. Kawaguchi-Imada and N. Hirao and T. Ohashi and D. Ito and T. Kubo and M. Matsushita and M. Nohara and K. Matsubayashi and N. Katayama},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.07106},
  eprint = {2609.07106},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.07106},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Coupled structural and electronic evolution under pressure in CuIr2Se4, CuRh2S4, and CuRh2Se4
AU  - M. Emi
AU  - M. Shiomi
AU  - K. Kojima
AU  - K. Sugimoto
AU  - T. Karasawa
AU  - H. Suzuki
AU  - M. Takahashi
AU  - K. Oka
AU  - H. Kadobayashi
AU  - S. Kawaguchi-Imada
AU  - N. Hirao
AU  - T. Ohashi
AU  - D. Ito
AU  - T. Kubo
AU  - M. Matsushita
AU  - M. Nohara
AU  - K. Matsubayashi
AU  - N. Katayama
PY  - 2026
DA  - 2026/09/07
PB  - arXiv
DO  - 10.48550/arxiv.2609.07106
UR  - https://arxiv.org/abs/2609.07106
AB  - Spinel chalcogenides provide a platform for investigating the interplay among metallic, superconducting, and pressure-induced insulating states. Here, we combine synchrotron powder X-ray diffraction and electrical-resistivity measurements to investigate the pressure evolution of CuIr2Se4, CuRh2S4, and CuRh2Se4 over pressure ranges extending beyond those previously explored. High-pressure diffraction reveals closely related monoclinic supercells in all three compounds. For CuIr2Se4 and CuRh2S4, constrained profile fits based on structural models relaxed using density functional theory are compatible with Phase-IV-type bond-disproportionated structures, whereas the data for CuRh2Se4 establish a compatible monoclinic unit cell without resolving its atomic-scale ordering pattern. Insulating-like transport develops abruptly over a narrow pressure range in CuIr2Se4 but more gradually over broader pressure ranges in the Rh-based compounds, in close correspondence with their respective structural transformations. We also establish previously unreported bulk superconductivity in CuIr2Se4 at ambient pressure: zero resistance is attained at 0.29 K, and the accompanying ac diamagnetic response is consistent with nearly complete superconducting shielding. These results establish a close relationship between the formation of the high-pressure monoclinic phases and the evolution toward insulating transport, and demonstrate that transition-metal and chalcogen substitutions tune the characteristic pressure scales and the competition with superconductivity within a closely related structural framework.
ER  -

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