Ultrafast Formation of Jahn–Teller Polarons Revealed by State-Selective Excitation in Correlated Spinel Co 3 O 4
Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Jahn–Teller polarons are quasiparticles that stem from symmetry breaking and strong local electron–phonon coupling. They originate from an excess charge carrier being dressed by a local lattice distortion, caused by the Jahn–Teller effect, and they critically impact electrical, structural, and magnetic properties in transition metal oxides. The observation of the microscopic steps involved in their formation is essential for enabling control over material properties through the targeted activation of local, site-specific modifications with light pulses. While Jahn–Teller distortion associated with polaron formation was predicted to contribute significantly to changes in electronic band gap and optical properties in Co 3 O 4, its experimental observation remains elusive, requiring signatures of local symmetry reduction. In this work, we demonstrate Jahn–Teller polaron formation in spinel Co 3 O 4 . By exciting electronic transitions at 3.10 eV and 1.55 eV, we target either the O h Cobalt(III) or the T d Cobalt(II) ions, and drive the subsequent coherent responses of the system through two different pathways. For the former, we demonstrate that ligand-to-metal charge transfer leads to Jahn–Teller polaron formation, which is linked to the deformation potential and magnetoelastic coupling. For the latter, we identify the coherent excitation of a T 2g phonon mode launched by on-site d-d electronic transitions. Key to our observations is the ability to target site-specific electronic excitations in spinel Co 3 O 4 using ultrafast optical pulses, while monitoring the ensuing low-energy collective modes through the coherent time-domain response of the material. Our approach, which combines the comparative analysis of experimental fingerprints with the support from density functional theory calculations, is broadly applicable to systems in which Jahn–Teller polaron physics has been theoretically predicted but remains experimentally unverified, and it underscores the potential of electronic-state targeting as a route to selectively excite and probe quasiparticle dynamics in solids.
DOI: 10.1021/jacs.5c23346
Authors: Simone Restelli, Oliviero Cannelli, Nicola Colonna, Carmelo Grova, Paolo Usai, Michele Puppin, Mounir Mensi, Francesco Barantani, Yue Meng, Jérémie Teyssier, Malte Oppermann, Francesco Pennacchio, Camila Bacellar, Jérémy R. Rouxel, Ludmila Diniz Leroy, Oleg Dogadov, Natacha Ohannessian, Daniele Pergolesi, Pietro Galinetto, Przemysław Piekarz, Andrzej Ptok, Swati Chaudhary, Gregory A. Fiete, Majed Chergui, Edoardo Baldini, Giulia F. Mancini
Institutions: University of Pavia, Louisiana State University, École Polytechnique Fédérale de Lausanne, Paul Scherrer Institute, The University of Texas at Austin, University of Geneva, University of Basel, Argonne National Laboratory, Institute of Nuclear Physics, Polish Academy of Sciences, Northeastern University, Massachusetts Institute of Technology, Elettra-Sincrotrone Trieste S.C.p.A.
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Funders: National Science Foundation, U.S. Department of Energy, W. M. Keck Foundation, Alexander von Humboldt-Stiftung, Massachusetts Institute of Technology, Universität Basel, University of Texas at Austin, Elettra-Sincrotrone Trieste, Laserlab-Europe, European Commission, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Fondazione Cariplo, Paul Scherrer Institut, Università degli Studi di Pavia, Université de Genève, Ministero dell'Università e della Ricerca, Research Executive Agency, Deutsches Elektronen-Synchrotron, National Center of Competence in Research Materials’ Revolution: Computational Design and Discovery of Novel Materials, Division of Materials Research, Nuclear Physics, Chemical Sciences, Geosciences, and Biosciences Division, Army Research Office, Argonne National Laboratory, HORIZON EUROPE European Research Council
Awards: G102163711, G107546177, Element-selective impulsive electronic and vibrational spectroscopy in iron-sulfur clusters, G1313983767, G1419553934, G1523517880, G1664757510, G1760870335, G1793864902, G2526629348, G262962599, Commentaire scientifique de l'évangile selon Luc (ch. 9ss)., G2978038238, G3075337988, G3188738659, G320509038, G3432274350, G3482134774, G3589692066, The Integrated Initiative of European Laser Research Infrastructures, G4303546637, X-ray spectroscopy of molecular chirality in solutions, NCCR MARVEL: Materials’ Revolution: Computational Design and Discovery of Novel Materials (phase III), G4479404689, Molecular Ultrafast Science and Technology (MUST), G4793784725, G5092458764, G5122498638, G513797252, Real-time, High-throughput, Coherent X-ray Microscopy: from Large-Scale Installations to Tabletop Device, G6256534168, G656611962, G665223801, G6671297155, G6848031779, Cavity-Mediated Engineering of Quantum Materials, G7185950326, CAREER: Nonequilibrium Dynamics of Spin-Correlated Excitons in van der Waals Magnets, G7658037602, G8075094277, G8098535155, G8115522821, Nonequilibrium Control of Magnetism and Topology Through Selective Phonon Excitations, G838185036, Center for Dynamics and Control of Materials, G969889393, G972786147
OpenAlex ID: W7147574605