Factorized ground state for a general class of ferrimagnets

Rezai, Mohammad; Langari, A.; Abouie, J.

doi:10.1103/physrevb.81.060401

Cited by 19 publications

(33 citation statements)

References 21 publications

(30 reference statements)

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“…Although the above general explanation is applied to the strong magnetic field regime the saturated plateau (M x = 1.5) can also be explained from another point of view. An eigenstate with full saturation is classified as a factorized state 23 in which all spins align in the direction of the magnetic field. As a general argument, it has been shown in Ref.…”

Section: Density Matrix Renormalization Group Resultsmentioning

confidence: 99%

Phase diagram of theXXZferrimagnetic spin-(1/2, 1) chain in the presence of transverse magnetic field

Langari¹,

Abouie²,

Asadzadeh³

et al. 2011

J. Stat. Mech.

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We investigate the phase diagram of an anisotropic ferrimagnetic spin-(1/2, 1) in the presence of a non-commuting (transverse) magnetic field. We find a magnetization plateau for the isotropic case while there is no plateau for the anisotropic ferrimagnet. The magnetization plateau can appear only when the Hamiltonian has the U(1) symmetry in the presence of the magnetic field. The anisotropic model is driven by the magnetic field from the Néel phase for low fields to the spin-flop phase for intermediate fields and then to the paramagnetic phase for high fields. We find the quantum critical points and their dependence on the anisotropy of the aforementioned field-induced quantum phase transitions. The spin-flop phase corresponds to the spontaneous breaking of Z2 symmetry. We use the numerical density matrix renormalization group and analytic spin wave theory to find the phase diagram of the model. The energy gap, sublattice magnetization, and total magnetization parallel and perpendicular to the magnetic field are also calculated. The elementary excitation spectrums are obtained via the spin wave theory in the three different regimes depending on the strength of the magnetic field.

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Section: Density Matrix Renormalization Group Resultsmentioning

confidence: 99%

Phase diagram of theXXZferrimagnetic spin-(1/2, 1) chain in the presence of transverse magnetic field

Langari¹,

Abouie²,

Asadzadeh³

et al. 2011

J. Stat. Mech.

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“…The factorizing fields depend on the coupling constants J x,y,z , the spin magnitudes and the ratio of two magnetic fields. At zero staggered field, the parameter ω is 1 thenσ is σ and we retrieve the results of Ref., 10) The factorizing uniform and staggered fields are written in terms of h σ as follows:…”

Section: Nearest Antiferromagnetic and Next Nearest Ferromagnetic Intmentioning

confidence: 99%

Ground State Factorization of Heterogeneous Spin Models in Magnetic Fields

Abouie

Rezai

Langari

2012

Progress of Theoretical Physics

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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: 370, 379 §1. Introduction Quantum nature of a spin system strongly affects its low temperature behavior and the corresponding exotic phases. The ground state is the sole candidate to explain the quantum phase transition 1) which takes place at zero temperature; however, the low temperature properties are highly influenced by this state. The strongly correlated nature of the anisotropic quantum spin models prohibits us to know the ground state exactly except in few special cases. 2), 3) At some particular point of the parameter space the quantum correlations vanish and the ground state can be obtained in terms of the direct product of single particle states exactly. This state is called a factorized state (FS) and the corresponding magnetic field is the factorizing field. The entanglement is exactly zero at the factorizing field which corresponds to the associated entanglement phase transition. An exact ground state even at particular values of the parameters gives several information on the different properties of the model and can be implemented to initiate a perturbation theory for more knowledge of the neighboring phases. 4), 5) Kurmann et al. 6) introduced the factorized ground state of a homogeneous spin- * )

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“…At the factorizing field (also called classical field, h cl = h f = 2(1 + ∆)) [9] the ground state takes a product form [9,13] and its entanglement is zero. In Fig.…”

Section: Zero Temperature Phase Diagrammentioning

confidence: 99%

“…The investigation in this direction resumed recently following the seminal work of J. Kurman and his collaboratores [9]. Several efforts have been devoted to this direction which is important for condensed matter researchers, i.e finding an exact (factorized) ground state even at particular values of the coupling constants [10,11,12,13]. The factorized (exact) ground state is an accurate starting point to investigate the quantum nature of a phase close to the factorizing point in addition to some exact knowledge which gives at the factorized point.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic behavior of theXXZHeisenbergs= 1/2 chain around the factorizing magnetic field

Abouie¹,

Langari²,

Siahatgar³

2010

J. Phys.: Condens. Matter

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Abstract. We have investigated the zero and finite temperature behaviors of the anisotropic antiferromagnetic Heisenberg XXZ spin-1/2 chain in the presence of a transverse magnetic field (h). The attention is concentrated on an interval of magnetic field between the factorizing field (h f ) and the critical one (h c ). The model presents a spin-flop phase for 0 < h < h f with an energy scale which is defined by the long range antiferromagnetic order while it undergoes an entanglement phase transition at h = h f . The entanglement estimators clearly show that the entanglement is lost exactly at h = h f which justifies different quantum correlations on both sides of the factorizing field. As a consequence of zero entanglement (at h = h f ) the ground state is known exactly as a product of single particle states which is the starting point for initiating a spin wave theory. The linear spin wave theory is implemented to obtain the specific heat and thermal entanglement of the model in the interested region. A double peak structure is found in the specific heat around h = h f which manifests the existence of two energy scales in the system as a result of two competing orders before the critical point. These results are confirmed by the low temperature Lanczos data which we have computed.

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Factorized ground state for a general class of ferrimagnets

Cited by 19 publications

References 21 publications

Phase diagram of theXXZferrimagnetic spin-(1/2, 1) chain in the presence of transverse magnetic field

Phase diagram of theXXZferrimagnetic spin-(1/2, 1) chain in the presence of transverse magnetic field

Ground State Factorization of Heterogeneous Spin Models in Magnetic Fields

Thermodynamic behavior of theXXZHeisenbergs= 1/2 chain around the factorizing magnetic field

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