Phase diagram and critical properties of the frustrated Kondo necklace model in a magnetic field

TL;DR

This paper investigates the phase diagram and critical behavior of the frustrated Kondo necklace model at half saturation magnetization, revealing three distinct phases and their boundaries using bosonization and level spectroscopy methods.

Contribution

It provides a detailed phase diagram of the frustrated Kondo necklace model, identifying phase boundaries and critical properties through advanced analytical and numerical techniques.

Findings

Identification of three phases: dimer, Néel, and Tomonaga-Luttinger liquid.

Determination of phase boundary lines using level spectroscopy.

Effective description of the model as a quantum sine-Gordon model.

Abstract

The critical properties of the frustrated Kondo necklace model with a half saturation magnetization ($m=1/2$) have been studied by means of an exact-diagonalization method. It is shown from bosonization technique that the model can be effectively expressed as a quantum sine-Gordom model. Thus it may show three (dimer plateau, N{\'e}el plateau and Tomonaga-Luttinger liquid) phases due to competitions among the Ising anisotropy $\Delta$, and the nearest- and next-nearest-neighbor exchange interactions $J_1$ and $J_2$. The boundary lines on the $\Delta-J_2/J_1$ phase diagram separating the three phases are determined by the method of level spectroscopy based on the conformal field theory.