Antiferromagnetic sawtooth chain with spin-½ and spin-1 sites

Ravi Chandra, V. ; Sen, Diptiman ; Ivanov, N. B. ; Richter, J. (2004) Antiferromagnetic sawtooth chain with spin-½ and spin-1 sites Physical Review B: Condensed Matter and Materials Physics, 69 (21). 214406_1-214406_13. ISSN 1098-0121

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Official URL: http://prb.aps.org/abstract/PRB/v69/i21/e214406

Related URL: http://dx.doi.org/10.1103/PhysRevB.69.214406

Abstract

We study the low-energy properties of a sawtooth chain with spin-1's at the bases of the triangles and spin-½'s at the vertices of the triangles. The spins have Heisenberg antiferromagnetic interactions between nearest neighbors, with a coupling J2 between a spin-1 and a spin-½, and a coupling J1=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 J2=3.8, whereas for larger J2 the system exhibits a ferrimagnetic ground state characterized by a net ferromagnetic moment per unit cell of ½. In the region of small interactions J2, the mixed spin sawtooth chain maps on to an effective isotropic spin model representing two weakly interacting and frustrated spin-½ Heisenberg chains composed of spin-½ 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 J2=2.

Item Type:Article
Source:Copyright of this article belongs to The American Physical Society.
ID Code:45559
Deposited On:28 Jun 2011 05:43
Last Modified:18 May 2016 01:47

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