Electron-polaron dichotomy of charge carriers in perovskite oxides
Published in Communications Physics, 2020
Many transition metal oxides (TMOs) are Mott insulators due to strong Coulomb repulsion between electrons, and exhibit metal-insulator transitions (MITs) whose mechanisms are not always fully understood. Unlike most TMOs, minute doping in CaMnO 3 induces a metallic state without any structural transformations. This material is thus an ideal platform to explore band formation through the MIT. Here, we use angle-resolved photoemission spectroscopy to visualize how electrons delocalize and couple to phonons in CaMnO 3 . We show the development of a Fermi surface where mobile electrons coexist with heavier carriers, strongly coupled polarons. The latter originate from a boost of the electron-phonon interaction (EPI). This finding brings to light the role that the EPI can play in MITs even caused by purely electronic mechanisms. Our discovery of the EPI-induced dichotomy of the charge carriers explains the transport response of Ce-doped CaMnO 3 and suggests strategies to engineer quantum matter from TMOs.
Recommended citation: M. Husanu, L. Vistoli, C. Verdi, A. Sander, V. Garcia, J. Rault, F. Bisti, L. Lev, T. Schmitt, F. Giustino, A. Mishchenko, M. Bibes, V. Strocov, "Electron-polaron dichotomy of charge carriers in perovskite oxides." Communications Physics 1, 62, (2020).
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