Unconventional phases of the alternating-spin Heisenberg chain with extra three-body exchange terms

18th International School on Condensed Matter Physics: "Challenges of Nanoscale Science: Theory, Materials, Applications"

Ivanov, N.B.^1,2 ; Schnack, J.^1

Fakultät für Physik, Universität Bielefeld, Postfach 100131, Bielefeld

D-33501, Germany^1

ISSP, Bulgarian Academy of Sciences, Tzarigradsko chaussee 72, Sofia

1784, Bulgaria^2

关键词: Density matrix renormalization group;    Exact diagonalization;    Heisenberg chains;    Nearest neighbor clustering;    Nearest neighbors;    Spin configurations;    Spin-liquid phase;    Three-body interaction;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/558/1/012015/pdf
DOI  :  10.1088/1742-6596/558/1/012015

来源: IOP

【 摘 要 】

The Heisenberg chain with alternating site spins (S,σ) (1, 1/2) defines a realistic prototype model admitting extra isotropic three-body exchange terms which drive the chain into exotic quantum phases. In this paper, we focus on the non-magnetic part of the phase diagram. Based on numerical density-matrix renormalization group and exact-diagonalization calculations, we demonstrate that the nearest-neighbor three-body interaction stabilizes (i) a critical spin liquid phase described by two Gaussian conformal theories as well as (ii) a critical nematic-like phase characterized by dominant quadrupolar S-spin fluctuations. The emergence of these phases reflects some specific features of the three-body terms such as the promotion of local collinear spin configurations and the enhanced tendency towards nearest- neighbor clustering of the spins.