Exact ground states with deconfined gapless excitations for the 3 leg spin-1/2 tube

Abstract

We consider a spin-1/2 tube (a three-leg ladder with periodic boundary conditions) with a Hamiltonian given by two projection operators - one on the triangles, and the other on the square plaquettes on the side of the tube - that can be written in terms of Heisenberg and four-spin ring exchange interactions. We identify 3 phases: (i) for strongly antiferromagnetic exchange on the triangles, an exact ground state with a gapped spectrum can be given as an alternation of spin and chirality singlet bonds between nearest triangles; (ii) for ferromagnetic exchange on the triangles, we recover the phase of the spin-3/2 Heisenberg chain; (iii) between these two phases, a gapless incommensurate phase exists. We construct an exact ground state with two deconfined domain walls and a gapless excitation spectrum at the quantum phase transition point between the incommensurate and dimerized phase.

5 pages, 5 figures, paper revised, references added

References in corpus (7)

• Frustrated three-leg spin tubes: from spin 1/2 with chirality to spin 3/2
• Quantum phase transitions of the asymmetric three-leg spin tube
• Low-lying excitations of the three-leg spin tube using the density-matrix renormalization group method
• Heat capacity uncovers physics of a frustrated spin tube
• Quantum spin nanotubes -- frustration, competing orders and criticalities
• Quantum phase transitions in three-leg spin tubes
• Klein spin model ground states on general lattices

Cited by in corpus (7)

• Spin-Chirality Separation and S_3-Symmetry Breakings in the Magnetization Plateau of the Quantum Spin Tube
• Exact spin-orbital separation in a solvable model in one dimension
• Magnetic phase diagram of the coupled triangular spin tubes for CsCrF4
• Dimerized ground states in spin-S frustrated systems
• Low-energy effective theory and two distinct critical phases in a spin-1/2 frustrated three-leg spin tube
• Inelastic Neutron Scattering in Weakly Coupled Triangular Spin Tubes CsCrF${}_4$
• An exact real-space renormalization method and applications