Study of an Antiferromagnetic Sawtooth Chain with Spin-1/2 and Spin-1 sites

Abstract

We study the low-energy properties of a sawtooth chain with spin-1's at the bases of the triangles and spin-1/2's at the vertices of the triangles. The spins have Heisenberg antiferromagnetic interactions between nearest neighbors, with a coupling J_2 between a spin-1 and a spin-1/2, and a coupling J_1 = 1 between two spin-1's. Analysis of the exact diagonalization data for periodic chains containing up to N=12 unit cells shows that the ground state is a singlet for exchange couplings up to approximately J_2 = 3.8, whereas for larger J_2, the system exhibits a ferrimagnetic ground state characterized by a net ferromagnetic moment per unit cell of 1/2. In the region of small interactions J_2, the mixed spin sawtooth chain maps on to an effective isotropic spin model representing two weakly interacting and frustrated spin-1/2 Heisenberg chains composed of spin-1/2 sites at odd and even vertices respectively. Finally, we study the phenomenon of a macroscopic magnetization jump which occurs if a magnetic field is applied with a value close to the saturation field for J_2 = 2.

arXiv commentRevTeX, 28 pages including 11 figures

References in corpus (15)

• Magnetization plateaus in spin chains: ``Haldane gap'' for half-integer spins
• Dimerization and Incommensurate Spiral Spin Correlations in the Zigzag Spin Chain: Analogies to the Kondo Lattice
• First excitations of the spin 1/2 Heisenberg antiferromagnet on the kagomé lattice
• Order versus Disorder in the Quantum Heisenberg Antiferromagnet on the Kagom{é} lattice: an approach through exact spectra analysis
• Macroscopic magnetization jumps due to independent magnons in frustrated quantum spin lattices
• Exact eigenstates and macroscopic magnetization jumps in strongly frustrated spin lattices
• Independent magnon states on magnetic polytopes
• Elementary excitations in the $\Delta$-chain
• On Quantum Solitons in the Sawtooth Lattice
• Quantum Topological Excitations: from the Sawtooth Lattice to the Heisenberg Chain
• On the origin of heavy quasiparticles in LiV_2O_4
• Kagom{é} Lattice Antiferromagnet Stripped to Its Basics
• Gapless Singlet modes in the Kagome strips: A study through DMRG and strong coupling analysis
• Evaluation of low-energy effective Hamiltonian techniques for coupled spin triangles
• A Semi-Classical Analysis of Order from Disorder

Cited by in corpus (17)

• Linear independence of localized magnon states
• Magnetization process of atacamite: a case of weakly coupled $S=1/2$ sawtooth chains
• Localized-magnon states in strongly frustrated quantum spin lattices
• Diamond chains with multiple-spin exchange interactions
• Thermodynamics of delta-chain with ferro- and antiferromagnetic interactions
• Flat-band spin dynamics and phonon anomalies of the saw-tooth spin-chain system Fe${}_2$O(SeO${}_3$)${}_2$
• Localized dynamics following a quantum quench in a non-integrable system: An example on the sawtooth ladder
• Frustrated spin ladder with alternating spin-1 and spin-1/2 rungs
• Entanglement and level crossings in frustrated ferromagnetic rings
• The delta-chain with ferro- and antiferromagnetic interactions in applied magnetic field
• Exact ground states for coupled spin trimers
• Magnetic phase separation in a frustrated ferrimagnetic chain under a magnetic field
• Disordered ground states in a quantum frustrated spin chain with side chains
• Anomalous thermodynamics of a quantum spin system with large residual entropy
• Anomalous fractional quantization in the kagomelike Heisenberg ladder: Emergence of the effective spin-1 chain
• Magnetic properties of delta- and kagome-like chains with competing interactions
• Magnetic properties of ferro-antiferromagnetic spin triangle chain