Phase diagram of the alternating-spin Heisenberg chain with extra isotropic three-body exchange interactions

TL;DR

This paper investigates the phase diagram of an alternating-spin Heisenberg chain with added isotropic three-body interactions, revealing new quantum phases and states through numerical methods.

Contribution

It introduces the first detailed study of isotropic three-body exchange effects in an alternating-spin Heisenberg chain, uncovering novel quantum phases and critical states.

Findings

Stabilization of partially-polarized states

Identification of a critical spin-liquid phase

Discovery of a critical nematic-like phase

Abstract

For the time being isotropic three-body exchange interactions are scarcely explored and mostly used as a tool for constructing various exactly solvable one-dimensional models, although, generally speaking, such competing terms in generic Heisenberg spin systems can be expected to support specific quantum effects and phases. The Heisenberg chain constructed from alternating S=1 and sigma=1/2 site spins defines a realistic prototype model admitting extra three-body exchange terms. Based on numerical density-matrix renormalization group (DMRG) and exact diagonalization (ED) calculations, we demonstrate that the additional isotropic three-body terms stabilize a variety of partially-polarized states as well as two specific non-magnetic states including a critical spin-liquid phase controlled by two Gaussinal conformal theories as well as a critical nematic-like phase characterized by dominant quadrupolar S-spin fluctuations. Most of the established effects are related to some specific features of the three-body interaction such as the promotion of local collinear spin configurations and the enhanced tendency towards nearest-neighbor clustering of the spins. It may be expected that most of the predicted effects of the isotropic three-body interaction persist in higher space dimensions.