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Journal Nature Communication 8, 15929 (2017)
Title Jahn-Teller distortion driven magnetic polarons in magnetite
Author H. Y. Huang , Z. Y. Chen , R. -P. Wang , F. M. F. de Groot , W. B. Wu , J. Okamoto , A. Chainani , A. Singh , Z. -Y. Li , J. -S. Zhou , H. -T. Jeng , G. Y. Guo , Je-Geun Park , L. H. Tjeng , C. T. Chen & D. J. Huang
The first known magnetic mineral, magnetite, has unusual properties, which have fascinated mankind for centuries; it undergoes the Verwey transition around 120 K with an abrupt change in structure and electrical conductivity. The mechanism of the Verwey transition, however, remains contentious. Here we use resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe2+ and Fe3+ states. Comparison of the experimental results with crystal-field multiplet calculations shows that the spin–orbital dd excitons of the Fe2+ sites arise from a tetragonal Jahn-Teller active polaronic distortion of the Fe2+O6 octahedra. These low-energy excitations, which get weakened for temperatures above 350 K but persist at least up to 550 K, are distinct from optical excitations and are best explained as magnetic polarons.