Exact degenerate ground states for the F-AF spin chain with bond alternation

Abstract

We investigate the $J_1$-$J_2$ spin chain consisting of spins with magnitude $\frac{1}{2}$. The nearest-neighbor and the next-nearest-neighbor exchange interactions are ferromagnetic and antiferromagnetic, respectively, and induce strong frustration. Both these interactions involve the bond alternation. We find exact solutions for all the degenerate ground states on the phase boundary of the ferromagnetic phase. The degeneracy remains irrespective of two parameters representing the bond alternation. The exact solutions are of closed forms for no bond alternation and of recursion formulae in general. The exact solutions are applicable to the $\Delta$ chain as a special case.

4 pages, 2 figures

References in corpus (4)

• Magnetic phase diagram of the S=1/2 antiferromagnetic zigzag spin chain in the strongly frustrated region: cusp and plateau
• Quantum vs. Classical Magnetization Plateaus of S=1/2 Frustrated Heisenberg Chains
• Fractional S^z excitation and its bound state around the 1/3 plateau of the S=1/2 Ising-like zigzag XXZ chain
• Disordered ground states in a quantum frustrated spin chain with side chains

Cited by in corpus (2)

• Entanglement and level crossings in frustrated ferromagnetic rings
• Topological Phases of Spin-1/2 Ferromagnetic--Antiferromagnetic Alternating Heisenberg Chains with Alternating Next-Nearest-Neighbour Interaction