The underlying mechanisms of the metal-insulator transition in correlated oxides are a rich source of interesting physics and a topic of long-standing investigation. Here, the authors use angle-resolved photoelectron spectroscopy to investigate changes in charge carrier properties and electron-phonon interactions as a function of Ce-doping across the metal-insulator transition in CaMnO3. 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.

Electron-polaron dichotomy of charge carriers in perovskite oxides

Bisti F;
2020

Abstract

The underlying mechanisms of the metal-insulator transition in correlated oxides are a rich source of interesting physics and a topic of long-standing investigation. Here, the authors use angle-resolved photoelectron spectroscopy to investigate changes in charge carrier properties and electron-phonon interactions as a function of Ce-doping across the metal-insulator transition in CaMnO3. 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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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11697/162562
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