Electron-polaron dichotomy of charge carriers in perovskite oxides

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 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.

Electron–Phonon Coupling and Electron–Phonon Scattering in SrVO3

“…Instead, we note that in recent years, the small polaron scenario has been used to describe ρ ( T ) of heavily doped manganites [ 33 , 63 ] or doped Mott insulators LaTiO 3 [ 35 , 36 ] and NdTiO 3 . [ 36 ] We focus now our attention on the relevant phonon energies ( ħω 0 ≈ 5–25 meV ≈ 60–290 K) extracted from the fits of ρ ( T ) of our films (Figure 6a ) and the observed variation with the tetragonal distortion c / a .…”

Fermi blockade of the strong electron–phonon interaction in modelled optimally doped high temperature superconductors

“…More generally, it is a long standing fundamental problem to reveal how the Migdal’s theorem 22 , 23 emerges at the large fermion concentration and eliminates the need for vertex corrections even for strong EPI, provided the Fermi-liquid state remains stable. Violations of the Migdal theorem in high temperature superconductors were discussed for decades 24 .…”

Barriers to carriers: faults and recombination in non-stoichiometric perovskite scintillators

“…However, recent studies indicate that NAMD without SOC effects can successfully capture the experimental trend of the non-radiative recombination rates in perovskites materials [11,12]. We also did not model the possibility of having explicit small polaron formation in these oxide materials [15].…”