Optically driven ultrafast lattice contraction in a topological crystalline insulator
Abstract
The ability to dynamically control topological order remains a central challenge in the exploration of quantum materials. Here, we investigate the lattice and electronic response of the topological crystalline insulator (TCI) Pb1−xSnxSe to ultrafast optical excitation using time- and angle-resolved photoemission spectroscopy (tr-ARPES) in combination with X-ray diffraction (XRD) and first-principles calculations. Static XRD measurements establish the lattice constant as the key control parameter for the topological transition, with a critical value ac=6.073 Åseparating the normal-insulator and topological phases. Despite generating electronic temperatures far above the topological-to-normal transition temperature Tc, optical excitation in the TCI phase does not induce a phase transition. Instead, it drives an ultrafast lattice contraction of Δa ≈ −0.45 pm within less than 1 ps that counteracts thermal expansion and prevents the system from reaching ac. The optical excitation therefore pushes the system deeper into the topological phase, providing a direct explanation for the absence of an optically driven transition. Total-energy calculations reveal that this behavior originates from the band inversion in the topological regime, which reverses the character of the photoinduced charge transfer and transiently strengthens atomic bonding. These findings identify band inversion as a mechanism that fundamentally alters the nonequilibrium lattice response, with general implications for ultrafast optical control of topological materials.
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BibTeX
@misc{berntsen2026optically,
title = {{Optically driven ultrafast lattice contraction in a topological crystalline insulator}},
author = {M. H. Berntsen and W. Chen and D. Phuyal and J. Wu and A. Grubišić-Čabo and M. Dendzik and Q. Guo and A. Orthaber and C. Li and R. M. Geilhufe and J. Weissenrieder and O. Tjernberg},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.16513},
eprint = {2610.16513},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.16513},
}
RIS
TY - UNPB
TI - Optically driven ultrafast lattice contraction in a topological crystalline insulator
AU - M. H. Berntsen
AU - W. Chen
AU - D. Phuyal
AU - J. Wu
AU - A. Grubišić-Čabo
AU - M. Dendzik
AU - Q. Guo
AU - A. Orthaber
AU - C. Li
AU - R. M. Geilhufe
AU - J. Weissenrieder
AU - O. Tjernberg
PY - 2026
DA - 2026/10/12
PB - arXiv
DO - 10.48550/arxiv.2610.16513
UR - https://arxiv.org/abs/2610.16513
AB - The ability to dynamically control topological order remains a central challenge in the exploration of quantum materials. Here, we investigate the lattice and electronic response of the topological crystalline insulator (TCI) Pb_1−xSn_xSe to ultrafast optical excitation using time- and angle-resolved photoemission spectroscopy (tr-ARPES) in combination with X-ray diffraction (XRD) and first-principles calculations. Static XRD measurements establish the lattice constant as the key control parameter for the topological transition, with a critical value a_c=6.073 Åseparating the normal-insulator and topological phases. Despite generating electronic temperatures far above the topological-to-normal transition temperature T_c, optical excitation in the TCI phase does not induce a phase transition. Instead, it drives an ultrafast lattice contraction of Δa ≈ −0.45 pm within less than 1 ps that counteracts thermal expansion and prevents the system from reaching a_c. The optical excitation therefore pushes the system deeper into the topological phase, providing a direct explanation for the absence of an optically driven transition. Total-energy calculations reveal that this behavior originates from the band inversion in the topological regime, which reverses the character of the photoinduced charge transfer and transiently strengthens atomic bonding. These findings identify band inversion as a mechanism that fundamentally alters the nonequilibrium lattice response, with general implications for ultrafast optical control of topological materials.
ER -