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Studies on a frustrated Heisenberg spin chain with alternating ferromagnetic and antiferromagnetic exchanges

Sahoo, Shaon and Goli, Durga Prasad VML and Sen, Diptiman and Ramasesha, S (2014) Studies on a frustrated Heisenberg spin chain with alternating ferromagnetic and antiferromagnetic exchanges. In: JOURNAL OF PHYSICS-CONDENSED MATTER, 26 (27).

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Official URL: http://dx.doi.org/10.1088/0953-8984/26/27/276002

Abstract

We study Heisenberg spin-1/2 and spin-1 chains with alternating ferromagnetic (J(1)(F)) and antiferromagnetic (J(1)(A)) nearest-neighbor interactions and a ferromagnetic next-nearest-neighbor interaction (J(2)(F)). In this model frustration is present due to the non-zero J(2)(F). The model with site spin s behaves like a Haldane spin chain, with site spin 2s in the limit of vanishing J(2)(F) and large J(1)(F)/J(1)(A). We show that the exact ground state of the model can be found along a line in the parameter space. For fixed J(1)(F), the phase diagram in the space of J(1)(A)-J(2)(F) is determined using numerical techniques complemented by analytical calculations. A number of quantities, including the structure factor, energy gap, entanglement entropy and zero temperature magnetization, are studied to understand the complete phase diagram. An interesting and potentially important feature of this model is that it can exhibit a macroscopic magnetization jump in the presence of a magnetic field; we study this using an effective Hamiltonian.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the IOP PUBLISHING LTD, ENGLAND.
Keywords: frustrated spin systems; alternating spin model; quantum phase transition; macroscopic magnetization jump
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Depositing User: Id for Latest eprints
Date Deposited: 19 Aug 2014 11:22
Last Modified: 19 Aug 2014 11:22
URI: http://eprints.iisc.ac.in/id/eprint/49623

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