Doped Mott Insulators in (111) Bilayers of Perovskite Transition-Metal Oxides with a Strong Spin-Orbit Coupling

TL;DR

This paper investigates the electronic properties of (111) bilayer Mott insulators in perovskite transition-metal oxides with strong spin-orbit coupling, revealing potential for exotic phases like Kitaev spin liquids and superconductivity upon doping.

Contribution

It derives effective Hamiltonians for these systems, identifies a Kitaev spin liquid phase, and suggests doping-induced superconductivity, providing a theoretical framework for experimental exploration.

Findings

Existence of a Kitaev spin liquid phase in certain parameter regimes.

Potential for doping-induced superconductivity in these Mott insulators.

Derived low-energy models incorporating strong spin-orbit coupling effects.

Abstract

The electronic properties of Mott insulators realized in (111) bilayers of perovskite transition-metal oxides are studied. The low-energy effective Hamiltonians for such Mott insulators are derived in the presence of a strong spin-orbit coupling. These models are characterized by the antiferromagnetic Heisenberg interaction and the anisotropic interaction whose form depends on the $d$ orbital occupancy. From exact diagonalization analyses on finite clusters, the ground state phase diagrams are derived, including a Kitaev spin liquid phase in a narrow parameter regime for $t_{2g}$ systems. Slave-boson mean-field analyses indicate the possibility of novel superconducting states induced by carrier doping into the Mott-insulating parent systems, suggesting the present model systems as unique playgrounds for studying correlation-induced novel phenomena. Possible experimental realizations are also discussed.