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Antiferromagnetic sawtooth chain with spin-1/2 and spin-1 sites

Chandra, Ravi V and Sen, Diptiman and Ivanov, NB and Richter, J (2004) Antiferromagnetic sawtooth chain with spin-1/2 and spin-1 sites. In: Physical Review B (Condensed Matter and Materials Physics -1(I)), 69 (21). 214406-1-13.

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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'sat 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- 1/2, 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 1/2. 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- 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 J2 = 2.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to American Physical Society (APS)
Department/Centre: Division of Physical & Mathematical Sciences > Centre for Theoretical Studies
Date Deposited: 23 Aug 2004
Last Modified: 19 Sep 2010 04:14
URI: http://eprints.iisc.ernet.in/id/eprint/1315

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