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.
Cite
@article{arxiv.cond-mat/0307492,
title = {Study of an Antiferromagnetic Sawtooth Chain with Spin-1/2 and Spin-1 sites},
author = {V. Ravi Chandra and Diptiman Sen and N. B. Ivanov and J. Richter},
journal= {arXiv preprint arXiv:cond-mat/0307492},
year = {2009}
}
Comments
RevTeX, 28 pages including 11 figures