Macroscopic degeneracy of ground state in the frustrated Heisenberg diamond chain

Abstract

The spin-$\frac{1}{2}$ Heisenberg diamond chain with ferro- and antiferromagnetic exchange interactions is studied. The phase boundary in the parametric space of these interactions is determined, where the transition between the ferromagnetic and other (singlet or ferrimagnetic) ground state phases occurs. On this phase boundary there is a dispersionless (flat) energy band in the one-magnon spectrum and these states can be represented as localized magnons in the trapping cells between neighboring diamonds. The ground state consists of the localized magnons and special magnon complexes and it is macroscopically degenerate. A remarkable feature of the model is the existence, on a certain part of the phase boundary, of two- and three-magnon localized states, forming flat bands in two- and three-magnon spectrum. All these localized states also belong to the ground state manifold, which turns out to be exactly the same as for the system of independent spins-$\frac{3}{2}$. This implies a large macroscopic degeneracy of the ground state $4^n$ ($n$ is number of diamonds in the chain) and a high residual entropy per spin $s_0=\frac{2}{3}\ln 2$.

27 pages, 13 figures

References in corpus (16)

• Strongly correlated flat-band systems: The route from Heisenberg spins to Hubbard electrons
• Exact low-temperature behavior of kagome antiferromagnet at high fields
• Magnetocaloric effect in one-dimensional antiferromagnets
• Exact eigenstates and macroscopic magnetization jumps in strongly frustrated spin lattices
• Flat-Band Ferromagnetism as a Pauli-Correlated Percolation Problem
• Magnetism and Thermodynamics of Spin-1/2 Heisenberg Diamond Chains in a Magnetic Field
• Dynamic and thermodynamic properties of the generalised diamond chain model for azurite
• Flatband generator in two dimensions
• Thermodynamics of delta-chain with ferro- and antiferromagnetic interactions
• Flat-band physics in the spin-1/2 sawtooth chain
• Frustrated magnetism of spin-1/2 Heisenberg diamond and octahedral chains as a statistical-mechanical monomer-dimer problem
• Ferrimagnetism in delta chain with anisotropic ferromagnetic and antiferromagnetic interactions
• The delta-chain with ferro- and antiferromagnetic interactions in applied magnetic field
• Semiquantitative theory for high-field low-temperature properties of a distorted diamond spin chain
• Two-dimensional spin models with macroscopic degeneracy
• Magnetization Plateau of the Distorted Diamond Spin Chain with Anisotropic Ferromagnetic Interaction

Cited by in corpus (2)

• Macroscopic ground state degeneracy of the ferro-antiferromagnetic Heisenberg model on diamond-decorated lattices
• Phase diagram and macroscopic ground state degeneracy of frustrated spin-1/2 anisotropic Heisenberg model on diamond-decorated lattices