Field-induced Bose-Einstein condensation and supersolid in the two-dimensional Kondo necklace

TL;DR

This paper investigates how an external magnetic field can induce Bose-Einstein condensation and supersolid phases in a two-dimensional Kondo necklace model, revealing a phase diagram relevant to nickelate materials.

Contribution

It introduces a tensor network approach to study the 2D Kondo necklace, unveiling a phase diagram and proposing a fermionic model for doping effects in BNOAS.

Findings

Identification of phases in the Kondo necklace model

Proposal of a fermionic model for doping-induced superconductivity

Relevance to nickelate compound experiments

Abstract

The application of an external magnetic field of sufficient strength to a spin system composed of a localized singlet can overcome the energy gap and trigger bosonic condensation and so provide an alternative method to realize exotic phases of matter in real materials. Previous research has indicated that a spin Hamiltonian with on-site Kondo coupling may be the effective many-body Hamiltonian for $\text{Ba}_2\text{NiO}_2\text{(AgSe)}_2$ (BNOAS) and here we study such a Hamiltonian using a tensor network ansatz in two dimensions. Our results unveil a phase diagram which indicates the underlying phases of BNOAS. We propose, in response to the possible doping-induced superconductivity of BNOAS, a fermionic model for further investigation. We hope that our discovery can bring up further interest in both theoretical and experimental researches for related nickelate compounds.