Abstract
Delafossites represent natural heterostructures which can host rather different electronic characteristics in their constituting layers. The design of novel heterostructure architectures highlighting the competition between such varying layer properties is 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 PdCrO$_2$ and insulating AgCrO$_2$. Due to the sophisticated coupling between layers of strong and of weak internal electron-electron interaction, correlation-induced semimetals at ambient temperature and doped Mott-insulators at lower temperature are predicted. The unique electronic structure of delafossite heterostructures opens a door to research on novel challenging quantum matter.
Highlights
Delafossite oxides [1] ABO2, where A and B are different metallic elements, have gained ample renewed interest, mainly from two directions
PdCrO2 and AgCrO2 To set the stage, we first briefly focus on the electronic structure of the natural bulk systems PdCrO2 and AgCrO2
In this paper we have shown that tailored heterostructuring of metallic PdCrO2 and insulating AgCrO2 gives rise to a plethora of challenging physics
Summary
Delafossite oxides [1] ABO2, where A and B are different metallic elements, have gained ample renewed interest, mainly from two directions. Tuning and designing the different aspects of delafossites by further technological heterostructuring may open a route to challenging new materials with exceptional properties. Among these fascinating materials, the PdCrO2 compound stands further out as it unites high metallicity from the Pd+(4d9) planes with Mott-insulating CrO2 layers [8,9,10,11]. Replacing Pd by neighboring Ag formally leads to a closed 4d10 shell and, nonsurprisingly, AgCrO2 is insulating with a technologically interesting band gap of 1.68 eV [5] In both delafossites, the localized Cr spins order in an antiferromagnetic 120◦ manner below Néel temperatures 37.5 K (PdCrO2) and 21 K (AgCrO2).
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