Prog. Theor. Phys. Vol. 127 No. 2 (2012) pp. 315-330
Ground State Factorization of Heterogeneous Spin Models in Magnetic Fields
1Department of Physics, Institute for Advanced Studies in Basic
Sciences, Zanjan 45137-66731, Iran
2Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran
(Received October 15, 2011; Revised December 15, 2011)
The exact factorized ground state of a heterogeneous
(ferrimagnetic) spin model which is composed of two spins
(ρ, σ) has been presented in detail. The Hamiltonian is
not necessarily translational invariant and the exchange couplings
can be competing antiferromagnetic and ferromagnetic arbitrarily
between different sublattices to build many practical models such
as dimerized and tetramerized materials and ladder compounds.
The condition to get a factorized ground state is investigated for
non-frustrated spin models in the presence of a uniform and a
staggered magnetic field. According to the lattice model structure we have
categorized the spin models in two different classes and obtained
their factorization conditions. The first class contains models in
which their lattice structures do not provide a single uniform
magnetic field to suppress the quantum correlations. Some of these
models may have a factorized ground state in the presence of a uniform
and a staggered magnetic field. However, in the second class there
are several spin models in which their ground state could be
factorized whether a staggered field is applied to
the system or not. For the latter case, in the absence of a staggered
field the factorizing uniform field is unique. However, the degrees
of freedom for obtaining the factorization conditions are increased
by adding a staggered magnetic field.
Subject Index :
DOI : 10.1143/PTP.127.315
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