Magnetization Plateaus Induced by a Coupling to the Lattice

Vekua, T.; Cabra, D. C.; Dobry, A.; Gazza, C. J.; Poilblanc, Didier

doi:10.1103/physrevlett.96.117205

Cited by 27 publications

(37 citation statements)

References 29 publications

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“…Similar conclusions should apply to more complicated models, since the effects of other interactions such as e.g. a next-nearest neighbor interaction would be simply to enlarge the extension of the plateaux phases and to modify the magnitude of the spin gaps [15].…”

Section: Introductionmentioning

confidence: 66%

“…Following the usual procedure in the low energy limit, we bosonize the spin degrees of freedom at fixed magnetization M and the interaction term becomes [15] …”

Section: Bosonization Descriptionmentioning

confidence: 99%

“…which after a finite size scaling analysis and a square fit leads to δ 2 = a + b A 2 + c A In order to compare both approaches, we need to use the relation (15) between λ 1/3 and A 2 , together with the values of δ 2 obtained form DMRG. Following this approach, in Fig.…”

Section: Dmrg Analysismentioning

confidence: 99%

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Anharmonic effects in magnetoelastic chains

et al. 2011

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We describe a new mechanism leading to the formation of rational magnetization plateau phases, which is mainly due to the anharmonic spin-phonon coupling. This anharmonicity produces plateaux in the magnetization curve at unexpected values of the magnetization without explicit magnetic frustration in the Hamiltonian and without an explicit breaking of the translational symmetry. These plateau phases are accompanied by magneto-elastic deformations which are not present in the harmonic case.

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Section: Introductionmentioning

confidence: 66%

“…Following the usual procedure in the low energy limit, we bosonize the spin degrees of freedom at fixed magnetization M and the interaction term becomes [15] …”

Section: Bosonization Descriptionmentioning

confidence: 99%

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Anharmonic effects in magnetoelastic chains

et al. 2011

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“…[16] The role of the spin-lattice coupling in frustrated spin systems has been extensively considered in the absence of an external magnetic field for both 1D [17,18] and 2D systems. [19] More recently, the importance of lattice distortions for stabilizing magnetization plateaus has been discussed in a simple 1D spin model, [20] and in a classical Heisenberg model on a pyrochlore lattice. [21] In this Letter we investigate the possible occurrence of magnetization plateaus in the frustrated spin-1/2 Heisenberg model on the square lattice by the numerical analysis of the periodicity of the distortion pattern induced by spin-lattice coupling.…”

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confidence: 99%

Magnetoelastic effects and magnetization plateaus in two-dimensional systems

et al. 2007

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We show the importance of both strong frustration and spin-lattice coupling for the stabilization of magnetization plateaus in translationally invariant two-dimensional systems. We consider a frustrated spin-1/2 Heisenberg model coupled to adiabatic phonons under an external magnetic field. At zero magnetization, simple structures with two or at most four spins per unit cell are stabilized, forming dimers or 2 × 2 plaquettes, respectively. A much richer scenario is found in the case of magnetization m = 1/2, where larger unit cells are formed with non-trivial spin textures and an analogy with the corresponding classical Ising model is detectable. Specific predictions on lattice distortions and local spin values can be directly measured by X-rays and Nuclear Magnetic Resonance experiments.PACS numbers: 75.10. Jm, 71.27.+a, 74.20.Mn A magnetization plateau occurs when the magnetization remains constant over a range ∆h of applied magnetic fields. The width of the plateau can be expressed in term of the excitation spectrum ∆h = E(M + 1) − 2E(M ) + E(M − 1), where E(M ) is the total energy at fixed magnetization M (measured in units of gµ B ). This, in turn, implies that the energy (per site) as a function of the magnetization (per site) displays a cusp-like singularity in the thermodynamic limit. In general, plateaus are absent in classical models with magnetic ground states whenever the magnetization is not collinear with the field.[1] Instead, they identify particularly stable quantum phases characterized by a spin gap.Usually, gaps in the excitation spectrum directly reflect the structure of the primitive cell of the lattice according to the commensurability condition [2] ℓS(1 − m) = integer (1) where S is the magnitude of the spin, m the magnetization per site in units of gµ B S (i.e., the average onsite spin component parallel to the magnetic field), and ℓ the number of spins in the primitive cell. Some evidence for a m = 1/3 plateau has been proposed for the triangular lattice, [9,10] while in the square lattice, the m = 0 properties of the J 1 −J 2 model are still debated. Indeed, although for J 2 /J 1 ∼ 1/2 the ground state is believed to be disordered, the existence of a finite triplet gap is much less clear, [11,12] casting some doubt as to the possibility of having an m = 0 plateau. The interest in the J 1 −J 2 model has grown due to the recent discovery of two materials well described by a two-dimensional (2D) quantum antiferromagnet, i.e., Li 2 VOSiO 4 and VOMoO 4 . [13,14] Although the experimental magnetization curve of these compounds has not yet been considered, the magnetization properties of the J 1 −J 2 model have been recently considered by using exact diagonalization calculations, leading to some evidence in favor of a magnetization plateau at m = 1/2. [15] This outcome has been interpreted as a consequence of the emergence of a 2 × 2 super-cell. According to this scenario, inside each cell the magnetic moments acquire a preferential orientation along the direction of the magnetic field, lea...

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“…we take u j i as parameters, calculate the magnetic energy by DMRG, and minimize the total energy (magnetic + elastic) until convergence. Details of the self-consistent procedure are given elsewhere [13,14].…”

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confidence: 99%

Dimerization process and elementary excitations in spin–Peierls chains coupled by frustrated interactions

Mastrogiuseppe¹,

Gazza²,

Dobry

2008

J. Phys.: Condens. Matter

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Abstract. We consider the ground state and the elementary excitations of an array of spin-Peierls chains coupled by elastic and magnetic interactions. It is expected that the effect of the magnetic interchain coupling will be to reduce the dimerization amplitude and that of the elastic coupling will be to confine the spin one-half solitons corresponding to each isolated chain. We show that this is the case when these interactions are not frustrated. On the other hand, in the frustrated case we show that the amplitude of dimerization in the ground state is independent of the strength of the interchain magnetic interaction in a broad range of values of this parameter. We also show that free solitons could be the elementary excitations when only nearest neighbour interactions are considered. The case of an elastic interchain coupling is analyzed on a general energetic consideration. To study the effect of the magnetic interchain interaction the problem is simplified to a two-leg ladder which is solved using density matrix renormalization group (DMRG) calculations. We show that the deconfinement mechanism is effective even with a significantly strong antiferromagnetic interchain coupling. Elementary excitations of antiferromagnetic systems are spin-one magnons which are bosonic in character and correspond to flipping locally the spin of one electron. They give rise to a definite peak in the dynamical structure factor which is observed in neutron scattering measurements. In a one-dimensional antiferromagnet, this picture breaks down and the concept of fractionalized excitation has been proposed in the last years to explain the excitation spectra. The excitation spectrum of a 1D antiferromagnetic Heisenberg model is a paradigmatic example of a fractional quantum state. The elementary excitations are spin-1 2 spinons which are topological excitations identified as quantum domain walls. The spectral signal corresponding to the excitation of two spinons shows a highly dispersive continuum without a definite one-particle peak in the dynamic susceptibility. Measurements of the two-spinon continuum have been achieved in the quasi-one-dimensional antiferromagnetic system KCuF 3 [1]. Since the discovery of the cuprate superconductors an intense activity has been carried out to

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Magnetization Plateaus Induced by a Coupling to the Lattice

Cited by 27 publications

References 29 publications

Anharmonic effects in magnetoelastic chains

Anharmonic effects in magnetoelastic chains

Magnetoelastic effects and magnetization plateaus in two-dimensional systems

Dimerization process and elementary excitations in spin–Peierls chains coupled by frustrated interactions

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