Ground State Properties of the Doped Kitaev-Heisenberg Chain: Topological Superconducting and Mott Insulating Phases Driven by Magnetic Frustration

TL;DR

This study uses DMRG to explore doped Kitaev-Heisenberg chains, revealing how magnetic frustration induces topological superconductivity and Mott insulating phases, with potential implications for understanding exotic quantum states.

Contribution

It demonstrates that magnetic frustration can drive both superconducting and insulating phases in doped Kitaev systems, highlighting new mechanisms for topological and Mott phases.

Findings

Bond-directional exchange promotes pairing and topological superconductivity.

Superconductivity is stabilized by cooperative J and K exchanges.

A Mott insulator with hopping dimerization appears at quarter filling.

Abstract

We study the hole-doped Kitaev-Heisenberg chain using the density-matrix renormalization group. In the Kitaev-only limit, the bond-directional exchange itself promotes pairing, favoring spin-singlet and spin-triplet superconducting tendencies for antiferromagnetic and ferromagnetic Kitaev couplings, respectively, together with finite-size Majorana edge correlations suggestive of topological superconductivity. In the full Kitaev-Heisenberg chain, cooperative $J$ and $K$ exchanges broadly stabilize superconductivity, while competition between $J$ and $K$ induces a strong filling dependence and enables superconductivity even when both $J$ and $K$ are weak. At quarter filling, this competition produces a Mott insulator with spontaneous hopping dimerization. These results identify magnetic frustration as a common mechanism underlying superconducting and interaction-driven insulating phases in doped Kitaev systems.