Unconventional electron states in \u03b4-doped SmTiO3

Frank Lechermann

doi:10.1038/s41598-017-01847-5

Abstract

ABSTRACTThe Mott-insulating distorted perovskite SmTiO3, doped with a single SrO layer in a quantum-well architecture is studied by the combination of density functional theory with dynamical mean-field theory. A rich correlated electronic structure in line with recent experimental investigations is revealed by the given realistic many-body approach to a large-unit-cell oxide heterostructure. Coexistence of conducting and Mott-insulating TiO2 layers prone to magnetic order gives rise to multi-orbital electronic transport beyond standard Fermi-liquid theory. First hints towards a pseudogap opening due to electron-electron scattering within a background of ferromagnetic and antiferromagnetic fluctuations are detected.

Highlights

The Mott-insulating distorted perovskite SmTiO3, doped with a single SrO layer in a quantum-well architecture is studied by the combination of density functional theory with dynamical mean-field theory
The distorted perovskite SmTiO3 is a member of the R TiO3 (R: rare-earth element) series with formal Ti3+ − 3d(t21g) valence configuration and a Mott insulator at stoichiometry
Recent experimental work focusing on δ-doping SmTiO3 with a single SrO layer, exposed non-Fermi-liquid (NFL) character

Summary

Introduction

The Mott-insulating distorted perovskite SmTiO3, doped with a single SrO layer in a quantum-well architecture is studied by the combination of density functional theory with dynamical mean-field theory. Due to the complexity of the problem, many theories of doped correlated materials, especially on the model-Hamiltonian level, neglect details of the local-chemistry aspect This may be insufficient to elucidate the subtle energy-scale balancing of strongly correlated electrons systems prone to long-range order. The combination of first-principles density functional theory (DFT) with dynamical mean-field theory (DMFT) accounts for the interplay of bandstructure features and many-body effects beyond the realm of static-correlation approaches[4, 5] Allying these progresses by addressing a doped-Mott-insulator heterostructure via DFT+DMFT is suitable to reveal new insight into a hallmark challenge of interacting electron systems. The distorted perovskite SmTiO3 is a member of the R TiO3 (R: rare-earth element) series with formal Ti3+ − 3d(t21g) valence configuration and a Mott insulator at stoichiometry It displays antiferromagnetic (AFM) ordering below TN = 45 K. A subtle crossover to still intriguing transport behavior takes place by adding further doping layers[7,8,9]

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Results

Conclusion