Negative thermal expansion, lattice dynamics, and complex magnetism in TbFeO3
Abstract
We report a temperature-dependent investigation of orthoferrite TbFeO3 using x-ray diffraction, DC magnetization, and Raman scattering, complemented by room-temperature x-ray photoelectron spectroscopy. X-ray diffraction reveals negative thermal expansion over 5-300 K, with a small but systematic increase in unit-cell volume upon cooling in the absence of any structural phase transition. Raman scattering measurements identify the Raman-active phonon modes and show clear deviations from the conventional Klemens anharmonic decay model, particularly in phonon frequencies, indicating the presence of spin-phonon coupling. Two modes of Ag and B1g symmetry exhibit a crossover from Gaussian-dominated line shapes at low temperatures to mixed Gaussian-Lorentzian profiles at higher temperatures, reflecting a transition from inhomogeneous broadening to lifetime-driven dynamics. High-energy Raman spectra reveal two-magnon excitations associated with the Fe sublattice, consistent with linear spin-wave theory, whose spectral weight shows only weak temperature dependence. In addition, a broad Raman mode emerging below ∼ 175 K exhibits an order-parameter-like temperature evolution and coincides with the onset of phonon anomalies, while no corresponding strong anomaly is observed in the two-magnon response. Taken together, these results establish TbFeO3 as a system with pronounced interplay among lattice dynamics, spin correlations, and emergent local magnetic-lattice anomalies.
Versions
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BibTeX
@misc{farswan2026negative,
title = {{Negative thermal expansion, lattice dynamics, and complex magnetism in TbFeO$_3$}},
author = {Shubham Farswan and Reshma Kumawat and Dipankar Sarkar and Deeksha Singh and Md. Atif Hasan and Devajyoti Mukherjee and Kaushik Sen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.00469},
eprint = {2608.00469},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.00469},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Negative thermal expansion, lattice dynamics, and complex magnetism in TbFeO_3
AU - Shubham Farswan
AU - Reshma Kumawat
AU - Dipankar Sarkar
AU - Deeksha Singh
AU - Md. Atif Hasan
AU - Devajyoti Mukherjee
AU - Kaushik Sen
PY - 2026
DA - 2026/10/16
PB - arXiv
DO - 10.48550/arxiv.2608.00469
UR - https://arxiv.org/abs/2608.00469
AB - We report a temperature-dependent investigation of orthoferrite TbFeO_3 using x-ray diffraction, DC magnetization, and Raman scattering, complemented by room-temperature x-ray photoelectron spectroscopy. X-ray diffraction reveals negative thermal expansion over 5-300 K, with a small but systematic increase in unit-cell volume upon cooling in the absence of any structural phase transition. Raman scattering measurements identify the Raman-active phonon modes and show clear deviations from the conventional Klemens anharmonic decay model, particularly in phonon frequencies, indicating the presence of spin-phonon coupling. Two modes of A_g and B_1g symmetry exhibit a crossover from Gaussian-dominated line shapes at low temperatures to mixed Gaussian-Lorentzian profiles at higher temperatures, reflecting a transition from inhomogeneous broadening to lifetime-driven dynamics. High-energy Raman spectra reveal two-magnon excitations associated with the Fe sublattice, consistent with linear spin-wave theory, whose spectral weight shows only weak temperature dependence. In addition, a broad Raman mode emerging below ∼ 175 K exhibits an order-parameter-like temperature evolution and coincides with the onset of phonon anomalies, while no corresponding strong anomaly is observed in the two-magnon response. Taken together, these results establish TbFeO_3 as a system with pronounced interplay among lattice dynamics, spin correlations, and emergent local magnetic-lattice anomalies.
ER -