Raman spectroscopy and pressure-induced structural phase transition in UTe₂

Abstract

Results of the Raman scattering experiments, heat capacity measurements, ab initio simulations of the Raman spectra and pressure-induced phase transition in UTe₂ single crystal are reported. Assignment of symmetries to particular Raman-active phonons follows directly from a comparative analysis of the measured and calculated Raman spectra. Theoretically determined lattice contribution to the specific heat of UTe₂ allows for better description of its heat capacity measured over the temperatures ranging from 30 to 400 K. The orthorhombic-to-tetragonal phase transition pressure of 3.8 GPa is predicted at room temperature in very good agreement with the recent experimental studies. The phase transition remains almost phonon-independent with the transition pressure weakly temperature-dependent below 500 K. The strong local Coulomb correlations between U-5f electrons and spin−orbit interaction are shown to be important for realistic theoretical description of phonons and pressure-induced phase transition in UTe₂.

Graphical abstract

Keywords

Raman spectroscopy / heat capacity / phase transition / ab initio simulations

References

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Declarations

The authors declare no competing interests and no conflicts.

Data availability statement

All data that support the findings of this study are included within the article.

Acknowledgements

The Czech Science Foundation (GACR) project No. 22-22322S, the e-INFRA CZ (ID:90254) and QM4ST (CZ.02.01.01/00/22_008/0004572) projects supported by the Ministry of Education, Youth and Sports of the Czech Republic are acknowledged. The Interdisciplinary Center for Mathematical and Computational Modeling (ICM), Warsaw University, Poland are acknowledged for providing the computer facilities. Crystal growth, X-ray characterization and heat capacity measurements were performed in MGML (mgml.eu), which is supported within the program of Czech Research Infrastructures (Project No. LM2023065).

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