A metastable tetragonal phase in two-dimensional halide perovskite lattices driven by a coherent Higgs mode

Nature Materials (2026)Cite this article The optoelectronic properties of metal halide perovskites are defined by their coupled structural and photophysical properties, yet their lattice behaviour remains underexplored. Here, using impulsive stimulated Raman spectroscopy, we study light-induced phonon dynamics of two-dimensional butylammonium lead iodide ((BA)2PbI4) films under varying excitation intensities, photon energies and temperatures. We reveal that, whereas (BA)2PbI4 exhibits two thermally accessible orthorhombic phases, optically excited phonons transiently direct the lattice to a distinct, higher symmetry tetragonal phase. We show that bandgap oscillations arise from simultaneous distortions of in-plane and out-of-plane octahedral tilt angles with oscillations following a low-to-high symmetry pathway, marked by two vibrational frequencies independent of intensity—a signature of an optically excited Higgs mode. Notably, the Higgs mode at below-bandgap excitation induces a fourfold larger spectral shift than above-bandgap, where photogenerated charge carriers drive the system away from the optically induced tetragonal phase. This study illustrates how optomechanical coupling influences the optical properties of two-dimensional perovskites.This is a preview of subscription content, access via your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any timeSubscribe to this journal Receive 12 print issues and online access $259.00 per yearonly $21.58 per issueBuy this articleUSD 39.95Prices may be subject to local taxes which are calculated during checkoutAll data supporting the conclusions of this study are provided in the main manuscript and Supplementary Information. Further related datasets are available from the corresponding author upon reasonable request. Source data are provided with this paper.Dhanabalan, B. et al. Directional anisotropy of the vibrational modes in 2D-layered perovskites. ACS Nano 14, 4689–4697 (2020).Article CAS PubMed PubMed Central Google Scholar Zhang, T. et al. Regulation of the luminescence mechanism of two-dimensional tin halide perovskites. Nat. Commun. 13, 60 (2022).Article CAS PubMed PubMed Central Google Scholar Duan, J. et al. 2D hybrid perovskites: from static and dynamic structures to potential applications. Adv. Mater. 36, 2403455 (2024).Article CAS Google Scholar Kirstein, E. et al. Coherent spin dynamics of electrons in two-dimensional (PEA)2PbI4 perovskites. Nano Lett. 23, 205–212 (2023).Article CAS PubMed Google Scholar Lin, Q., Armin, A., Burn, P. L. & Meredith, P. Filterless narrowband visible photodetectors. Nat. Photonics 9, 687–694 (2015).Article Google Scholar Tsai, H. et al. High-efficiency two-dimensional Ruddlesden–Popper perovskite solar cells. Nature 536, 312–316 (2016).Article CAS PubMed Google Scholar Wang, N. et al. Perovskite light-emitting diodes based on solution-processed self-organized multiple quantum wells. Nat. Photonics 10, 699–704 (2016).Article CAS Google Scholar Cuthriell, S. A. et al. Nonequilibrium lattice dynamics in photoexcited 2D perovskites. Adv. Mater. 34, 2202709 (2022).Article CAS Google Scholar Guo, P. et al. Direct observation of bandgap oscillations induced by optical phonons in hybrid lead iodide perovskites. Adv. Funct. Mater. 30, 1907982 (2020).Article CAS Google Scholar Batignani, G. et al. Probing femtosecond lattice displacement upon photo-carrier generation in lead halide perovskite. Nat. Commun. 9, 1971 (2018).Article PubMed PubMed Central Google Scholar Thouin, F. et al. Phonon coherences reveal the polaronic character of excitons in two-dimensional lead halide perovskites. Nat. Mater. 18, 349–356 (2019).Article CAS PubMed Google Scholar Blancon, J.-C., Even, J., Stoumpos, C. C., Kanatzidis, M. G. & Mohite, A. D. Semiconductor physics of organic–inorganic 2D halide perovskites. Nat. Nanotechnol. 15, 969–985 (2020).Article CAS PubMed Google Scholar Tao, W., Zhang, C., Zhou, Q., Zhao, Y. & Zhu, H. Momentarily trapped exciton polaron in two-dimensional lead halide perovskites. Nat. Commun. 12, 1400 (2021).Article CAS PubMed PubMed Central Google Scholar Srimath Kandada, A. R. & Silva, C. Exciton polarons in two-dimensional hybrid metal-halide perovskites. J. Phys. Chem. Lett. 11, 3173–3184 (2020).Article CAS PubMed Google Scholar Zhang, X. et al. Ultrafast exciton–phonon coupling and energy transfer dynamics in quasi-2D layered Ruddlesden–Popper perovskites. Commun. Phys. 8, 71 (2025).Article CAS Google Scholar Debnath, T. et al. Coherent vibrational dynamics reveals lattice anharmonicity in organic–inorganic halide perovskite nanocrystals. Nat. Commun. 12, 2629 (2021).Article CAS PubMed PubMed Central Google Scholar Fu, J. et al. Electronic states modulation by coherent optical phonons in 2D halide perovskites. Adv. Mater. 33, 2006233 (2021).Article CAS Google Scholar Wall, S. et al. Ultrafast changes in lattice symmetry probed by coherent phonons. Nat. Commun. 3, 721 (2012).Article CAS PubMed Google Scholar Biswas, S. et al. Exciton polaron formation and hot-carrier relaxation in rigid Dion–Jacobson-type two-dimensional perovskites. Nat. Mater. 23, 937–943 (2024).Article CAS PubMed Google Scholar Qin, T. et al. Coherent exciton spin relaxation dynamics and exciton polaron character in layered two-dimensional lead-halide perovskites. ACS Nano 19, 4186–4194 (2025).Article CAS PubMed Google Scholar Zhou, C. & Zhou, J. Vibrational-anharmonicity-assisted phase transitions in perovskite oxides under terahertz irradiation. Phys. Rev. Appl. 20, 024020 (2023).Article CAS Google Scholar Zeiger, H. J. et al. Theory for displacive excitation of coherent phonons. Phys. Rev. B 45, 768–778 (1992).Article CAS Google Scholar Meier, Q. N. et al. Manifestation of structural Higgs and Goldstone modes in the hexagonal manganites. Phys. Rev. B 102, 014102 (2020).Article CAS Google Scholar Jain, A. et al. Higgs mode and its decay in a two-dimensional antiferromagnet. Nat. Phys. 13, 633–637 (2017).Article CAS Google Scholar Léonard, J., Morales, A., Zupancic, P., Donner, T. & Esslinger, T. Monitoring and manipulating Higgs and Goldstone modes in a supersolid quantum gas. Science 358, 1415–1418 (2017).Article PubMed Google Scholar Sherman, D. et al. The Higgs mode in disordered superconductors close to a quantum phase transition. Nat. Phys. 11, 188–192 (2015).Article CAS Google Scholar Haldar, A., Cortes, C. L., Gray, S. K., Sharifzadeh, S. & Darancet, P. Giant optomechanical coupling in the charge density wave state of tantalum disulfide. Preprint at https://arxiv.org/abs/2105.08874 (2021).Menahem, M. et al. Strongly anharmonic octahedral tilting in two-dimensional hybrid halide perovskites. ACS Nano 15, 10153–10162 (2021).Article CAS PubMed PubMed Central Google Scholar Dhamija, S., Bhutani, G., Jayachandran, A. & De, A. K. A revisit on impulsive stimulated Raman spectroscopy: importance of spectral dispersion of chirped broadband probe. J. Phys. Chem. A 126, 1019–1032 (2022).Article CAS PubMed Google Scholar Pedesseau, L. et al. Advances and promises of layered halide hybrid perovskite semiconductors. ACS Nano 10, 9776–9786 (2016).Article CAS PubMed Google Scholar Juraschek, D. M., Meier, Q. N. & Narang, P. Parametric excitation of an optically silent Goldstone-like phonon mode. Phys. Rev. Lett. 124, 117401 (2020).Article CAS PubMed Google Scholar Haldar, A., Huang, Z., Ma, X., Darancet, P. & Sharifzadeh, S. Excitation protocols for nonlinear phononics in bismuth and antimony. Phys. Rev. Mater. 8, 015202 (2024).Article CAS Google Scholar Ruppin, R. Electromagnetic energy density in a dispersive and absorptive material. Phys. Lett. A 299, 309–312 (2002).Article CAS Google Scholar Babaian, D., Hill, D., Yu, P. & Guha, S. Carrier relaxation and exciton dynamics in chemical-vapor-deposited two-dimensional hybrid halide perovskites. J. Mater. Chem. C 13, 193–202 (2025).Article CAS Google Scholar Drueke, E., Yang, J. & Zhao, L. Observation of strong and anisotropic nonlinear optical effects through polarization-resolved optical spectroscopy in the type-II Weyl semimetal Td-WTe2. Phys. Rev. B 104, 064304 (2021).Article CAS Google Scholar Giorgianni, F. et al. Terahertz displacive excitation of a coherent Raman-active phonon in V2O3. Commun. Phys. 5, 103 (2022).Article CAS Google Scholar Liu, S. et al. Nanoscale coherent phonon spectroscopy. Sci. Adv. 8, eabq5682 (2022).Article CAS PubMed PubMed Central Google Scholar Makino, K. et al. Anisotropic lattice response induced by a linearly-polarized femtosecond optical pulse excitation in interfacial phase change memory material. Sci. Rep. 6, 19758 (2016).Article CAS PubMed PubMed Central Google Scholar Warner, J. A., Patil, S. K. R., Khare, S. V. & Masiulaniec, K. C. Ab initio calculations for properties of MAX phases Ti2TlC, Zr2TlC, and Hf2TlC. Appl. Phys. Lett. 88, 101911 (2006).Article Google Scholar Kresse, G. & Hafner, J. Ab initio molecular dynamics for liquid metals. Phys. Rev. B 47, 558–561 (1993).Article CAS Google Scholar Kresse, G. & Furthmüller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 6, 15–50 (1996).Article CAS Google Scholar Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple [Phys. Rev. Lett. 77, 3865 (1996)]. Phys. Rev. Lett. 78, 1396–1396 (1997).Article CAS Google Scholar Kresse, G. & Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).Article CAS Google Scholar Kresse, G. & Hafner, J. Norm-conserving and ultrasoft pseudopotentials for first-row and transition elements. J. Phys. Condens. Matter 6, 8245 (1994).Article CAS Google Scholar Grimme, S. Semiempirical GGA-type density functional constructed with a long-range dispersion correction. J. Comput. Chem. 27, 1787–1799 (2006).Article CAS PubMed Google Scholar Momma, K. & Izumi, F. VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. Appl. Crystallogr. 44, 1272–1276 (2011).Article CAS Google Scholar Togo, A., Chaput, L., Tadano, T. & Tanaka, I. Implementation strategies in phonopy and phono3py. J. Phys. Condens. Matter 35, 353001 (2023).Article CAS Google Scholar Togo, A. First-principles phonon calculations with phonopy and phono3py. J. Phys. Soc. Jpn 92, 012001 (2023).Article Google Scholar Virtanen, P. et al. SciPy 1.0: fundamental algorithms for scientific computing in Python. Nat. Methods 17, 261–272 (2020).Article CAS PubMed PubMed Central Google Scholar Download referencesWork performed at the Center for Nanoscale Materials, a US Department of Energy Office of Science User Facility, was supported by the US DOE, Office of Basic Energy Sciences, under contract no. DE-AC02-06CH11357 (for A.S., S.A., P.D. and R.D.S.).

At Northwestern University, this work was supported by the National Science Foundation Chemical Science and Dynamics award no. 2404059 (to S.P. and R.D.S.) and the Department of Energy, Office of Science, Basic Energy Sciences, under grant no. SC0012541 (to S.P. and M.G.K. design, synthesis and physical properties of metal halides).Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL, USAAyushi Shukla, Sraddha Agrawal, Pierre Darancet & Richard D. SchallerDepartment of Chemistry, Northwestern University, Evanston, IL, USAShoshanna Peifer, Mercouri G. Kanatzidis & Richard D. SchallerInternational Institute for Nanotechnology, Evanston, IL, USAShoshanna Peifer, Mercouri G. Kanatzidis & Richard D. SchallerMaterials Science Division, Argonne National Laboratory, Lemont, IL, USAMercouri G. KanatzidisSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarSearch author on:PubMed Google ScholarA.S., S.P. and R.D.S. performed optical measurements. S.A. and P.D. performed theoretical calculations. S.P. and M.G.K. synthesized the materials. All authors contributed to the data interpretation and writing of the manuscript.Correspondence to Pierre Darancet or Richard D. Schaller.The authors declare no competing financial interests.Nature Materials thanks Paul Erhart, Gregory Scholes and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.Supplementary Figs. 1–12, Notes 1 and 2 and Tables 1–3.Atomic motion of the Pb–I framework associated with the 0.69 THz phonon mode, visualized by displacing atomic positions from −1 to +1 of the normalized eigenvector amplitude relative to the high-symmetry tetragonal phase.Atomic motion of the Pb–I framework associated with the 1.34 THz phonon mode, visualized by displacing atomic positions from −1 to +1 of the normalized eigenvector amplitude relative to the high-symmetry tetragonal phase.Atomic motion of the Pb–I framework associated with the 1.48 THz phonon mode, visualized by displacing atomic positions from −1 to +1 of the normalized eigenvector amplitude relative to the high-symmetry tetragonal phase.Atomic motion of the Pb–I framework associated with the Higgs mode, visualized as the combination of displacements along the 0.69, 1.34 and 1.48 THz phonon modes.Statistical source data.Statistical source data.Statistical source data.Statistical source data.Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.Reprints and permissionsShukla, A., Agrawal, S., Peifer, S. et al. A metastable tetragonal phase in two-dimensional halide perovskite lattices driven by a coherent Higgs mode. Nat. Mater. (2026). https://doi.org/10.1038/s41563-025-02433-1Download citationReceived: 26 March 2025Accepted: 04 November 2025Published: 05 January 2026Version of record: 05 January 2026DOI: https://doi.org/10.1038/s41563-025-02433-1Anyone you share the following link with will be able to read this content:Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative