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arXiv · 2004.02953

Electron-polaron dichotomy of charge carriers in perovskite oxides

Marius-Adrian Husanu·Lorenzo Vistoli·Carla Verdi·Anke Sander·Vincent Garcia·Julien Rault·Federico Bisti·Leonid L. Lev·Thorsten Schmitt·Feliciano Giustino·Andrey S. Mishchenko·Manuel Bibes·Vladimir N. Strocov
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Abstract

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 CaMnO3 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 CaMnO3. 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 CaMnO3 and suggests strategies to engineer quantum matter from TMOs.

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Marius-Adrian Husanu, Lorenzo Vistoli, Carla Verdi, Anke Sander, Vincent Garcia, Julien Rault, Federico Bisti, Leonid L. Lev, Thorsten Schmitt, Feliciano Giustino, Andrey S. Mishchenko, Manuel Bibes, Vladimir N. Strocov. 2020-04-06. Electron-polaron dichotomy of charge carriers in perovskite oxides. https://doi.org/10.1038/s42005-020-0330-6

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