Phase Diagram of the 1/2-1/2-1-1 Spin Chain by the Nonlinear Sigma Model

Abstract

We examine a periodic mixed spin chain with spin magnitudes 1/2 and 1 which are arrayed as 1/2-1/2-1-1. The three independent parameters are ratios of the four exchange couplings. We determine phase boundaries in the parameter space by using the gapless condition which was previously derived by mapping a general inhomogeneous spin chain to the nonlinear sigma model. We find two gapless boundaries separating three disordered phases. The features of the phases are explained in terms of singlet clusters.

2 pages, 2 Postscript figures, Submitted to Physica B (Proceedings of the 22nd International Conference on Low temperature Physics)

References in corpus (4)

• Alternating spin chains with singlet ground states
• Ground-State and Thermodynamic Properties of the Quantum Mixed Spin-1/2-1/2-1-1 Chain
• Non-Linear Sigma Model for Inhomogeneous Spin Chains
• Ground State Properties of One Dimensional S=1/2 Heisenberg Model with Dimerization and Quadrumerization

Cited by in corpus (3)

• Frustration Induced Quantum Phases in Mixed Spin Chain with Frustrated Side Chains
• Disordered ground states in a quantum frustrated spin chain with side chains
• Spin-Gap States of a Periodic Mixed Spin Chain