Theoretical design of highly correlated electron states in delafossite heterostructures

Abstract

Oxide delafossites represent natural heterostructures with often rather different electronic characteristics in their constituting layers. The design of novel heterostructure architectures highlighting the competition between such varying characteristics appears promising from the viewpoint of basic research as well as for future technological applications. By means of the combination of density functional theory and dynamical mean-field theory, we here unveil the formation of highly correlated electron states in delafossite heterostructures build from metallic PdCrO2 and insulating AgCrO2. Due to the sophisticated coupling between layers of strong and of weak internal interaction, correlation-induced semimetals at ambient temperature and doped Mott-insulators at low temperature are predicted in this study.

Effect of lattice strain on the electronic structure and magnetic correlations in infinite-layer (Nd,Sr)NiO2

“…B. Overall, our results for the PM phase agree well with those previously published [15,[47][48][49][50][51][52][53]. We observe that the in-plane compressive lattice strain does not qualitatively change the electronic structure and hence the quasiparticle Fermi surface of (Nd,Sr)NiO 2 for small Sr x.…”

“…Although the electronic structure and magnetic properties of NdNiO 2 (and related materials) have recently been widely discussed based on applications of band structure methods [14,[19][20][21][22][23][24][25][26][27][28][29][30][31], model techniques [16,[32][33][34][35], many-body perturbative GW [36,37], and DFT+dynamical mean-field theory (DFT+DMFT) [38][39][40][41][42][43][44][45] methods [46][47][48][49][50][51][52][53][54][55][56][57][58], the properties of Sr-doped NdNiO 2 are still poorly understood. For NdNiO 2 , DFT+DMFT calculations reveal significant correlation effects within the Ni 3d orbitals, which are complicated by large hybridization with the Nd 5d states [15,46,50].…”

Review on Developments and Progress in Nickelate‐Based Heterostructure Composites and Superconducting Thin Films

“…Reproduced under the terms of the Creative Commons Attribution 4.0 International License. [114] Copyright 2020, The Authors. Published by American Physical Society.…”

“…The Fermi surfaces in Figure 17b reveal two Fermi pockets around Γ and A points due to self-doping (SD) effect of Nd-5d orbitals. In Figure 17c,d, fourorbital Wannier downfolding [113] produces one effective spaceextending SD orbital with important Nd-d 3z 2 −r 2 and Nd-d xy feature, one fully occupied Ni-d 3z 2 −r 2 orbital, and one almost halfoccupied d-p hybridization orbital confined primarily to the NiO 2 planes with a mixing d x 2 −y 2 and p x(y) features, [114] which are in very good agreement with the orbital physics identified from above XAS and RIXS measurements. In other words, the infinite-layer nickelate possesses an intertwined electronic structure with both 3D metallic rare-earth 5d energy band and 2D Mott system.…”

Optimizing superconductivity: from cuprates via nickelates to palladates

“…While multi-orbital effects in nickelates are discussed [30][31][32][33][34][35][36][37][38][39], recent studies suggest that the single-band picture works well [4,5,40,41] -at least as a first-step approximation and when including the self-doping from the so-called A-pocket. A very recent magnetotransport experiment evidences strong similarities to cuprates and the validity of the single-band d x 2 −y 2 picture [42].…”