Collapse of Jahn-Teller phonons in La1−xSrxMnO3 with weak magnetoresistance

Journal Article · Sun Mar 01 00:00:00 UTC 2026 · Communications Materials

DOI: https://doi.org/10.1038/s43246-026-01139-4 · OSTI ID:3363914

Sterling, T ^[1]; Savici, Andrei T  ^[2]; Kajimoto, Ryoichi ^[3]; Ikeuchi, Kazuhiko ^[4]; Khan, Nazir ^[5]; Weber, Frank ^[5]; Reznik, Dmitry ^[6]

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1. University of Colorado, Boulder
2. ORNL
3. J-PARC Center, Japan Atomic Energy Agency
4. High Energy Accelerator Research Organization, KEK
5. Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, Kaiserstrasse 1
6. University of Colorado at Boulder

Perovskite manganites are quantum materials exhibiting competing interactions inducing colossal magnetoresistance (CMR). The prevailing theory of CMR highlights the essential role of electron-phonon coupling (EPC), but mounting evidence suggests the underlying mechanism is more complicated. Here, we investigate phonons and spin-phonon coupling in ferromagnetic CMR manganites La1−xSrxMnO3 (x=0.2,0.3) with relatively small CMR associated with melting of the magnetic order above room temperature. High-resolution neutron scattering experiments combined with density functional theory (DFT) show that the low-temperature ferromagnetic phase is conventional: neutron scattering from phonons agrees with DFT predictions and magnons follow sinusoidal dispersions. Fluctuating magnetic moments and low-energy phonons remain conventional in the high-temperature paramagnetic phase, indicating the Mn and La/Sr sublattices are not strongly perturbed by melting of ferromagnetism. In contrast, the Jahn–Teller-active optical oxygen vibrations collapse entirely above the Curie temperature, despite low CMR in these compositions, with some of the lost spectral weight reappearing as quasielastic scattering. We attribute this highly anomalous behavior to giant EPC in the charge and/or orbital channel. It drives cooperative diffusive motion of quasistatic carrier-trapping oxygen sublattice distortions once ferromagnetism disappears. We hypothesize the magnitude of magnetoresistance correlates with the rate of diffusion rather than with the strength of Jahn–Teller EPC.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 3363914
• Journal Information: Communications Materials, Journal Name: Communications Materials Vol. 7
• Country of Publication: United States
• Language: English