Staggered Dzyaloshinskii-Moriya Interaction Research Articles

Characterizing quantum criticality in the transverse field Ising model with staggered Dzyaloshinskii–Moriya interaction

The quantum criticality and entanglement properties are investigated in the one-dimensional spin-1/2 transverse field Ising model with staggered Dzyaloshinskii–Moriya interaction by utilizing the infinite-time evolving block decimation method. In this model, the staggered Dzyaloshinskii–Moriya interaction does not lead any new phase, while it only appears a phase transition line between Néel phase and paramagnetic phase. The behaviors of measurements of information illustrate the quantum phase transition and the existence of factorized points. The factorization phenomena is observed in the transverse Néel phase detecting by the entanglement quantities, in which the double degenerate ground state in transverse Néel phase is preserved by the Dzyaloshinskii–Moriya interaction also evidencing from the fidelity map. From the perspective of magnetism, the existence of chiral order and transverse Néel order suggests the helical magnetic structure induced by Dzyaloshinskii–Moriya interaction. The critical exponents and central charge keep invariant and convinced that the phase transitions belong to the Ising universality class. In contrary to the systems confined within central charge c=1, although the competition between the Dzyaloshinskii–Moriya interaction and external field changes the phase transition and entanglement properties, the quantum criticality seems independent of Dzyaloshinskii–Moriya interaction.

Low-temperature transport in the XY chain with staggered Dzyaloshinskii–Moriya interaction

The influence of staggered Dzyaloshinskii–Moriya (DM) interaction as well as external magnetic fields on transport properties of the spin-1/2 one-dimensional XY model with spatially modulated DM interaction which has been a complex topic in recent years is investigated. The longitudinal spin conductivity is calculated employing the fermionization approach, where we analyze the effect of the strength of DM interaction on continuum spin conductivity σreg(ω). In addition, the behavior of the Drude’s weight as a function of temperature T is presented, indicating a spin super-current behavior for all T.

Impact of Dzyaloshinskii-Moriya and anisotropic exchange interactions on the cubic kagome antiferromagnets Mn3X and Mn3AB

We perform a symmetry analysis of the ABC-stacked kagome planes of Mn atoms common to the $L1_2$ Mn$_3$X and antiperovskite Mn$_3$AB alloys. In addition to the single-ion-anisotropy and Kitaev-type anisotropic exchange known to stabilize 120{\deg} spin structures in these materials, our analysis results in a staggered Dzyaloshinskii-Moriya interaction and further gamma-type anisotropic exchange between nearest-neighbor spins. The presence of these new terms is shown not to affect the energetics of the 120{\deg} ground-states which explains their absence in prior minimal magnetic models. We go on to show, however, that their influence becomes apparent when spin-wave excitations are considered. We highlight these effects by calculating inelastic neutron scattering cross-sections to illustrate experimental means of probing the existence and relative strengths of these cloaked interactions.

Square skyrmion crystal in centrosymmetric systems with locally inversion-asymmetric layers

We investigate an instability toward a square-lattice formation of magnetic skyrmions in centrosymmetric layered systems. By focusing on a bilayer square-lattice structure with the inversion center at the interlayer bond instead of the atomic site, we numerically examine the stability of the square skyrmion crystal (SkX) based on an effective spin model with the momentum-resolved interaction in the ground state through the simulated annealing. As a result, we find that a layer-dependent staggered Dzyaloshinskii–Moriya (DM) interaction built in the lattice structure becomes the origin of the square SkX in an external magnetic field irrespective of the sign of the interlayer exchange interaction. The obtained square SkX is constituted of the SkXs with different helicities in each layer due to the staggered DM interaction. Furthermore, we show that the interplay between the staggered DM interaction and the interlayer exchange interaction gives rise to a double-Q state with a uniform component of the scalar chirality in the low-field region. The present results provide another way of stabilizing the square SkX in centrosymmetric magnets, which will be useful to explore further exotic topological spin textures.

Quantum criticality in spin-1/2 anisotropic XY model with staggered Dzyaloshinskii–Moriya interaction

By utilizing the infinite time evolving block decimation method in infinite matrix product state representation, the quantum criticality and critical exponents varying are investigated in the spin-1/2 anisotropic XY chain with staggered Dzyaloshinskii–Moriya interaction. The phase diagram is obtained from the entanglement measurement, where a XY phase line δ=0 separates the Néel phase. Along this critical line, the central charge c=1 is extracted from the finite entanglement and the finite correlation length. In addition, the characteristic critical exponents are obtained from the local transverse magnetization, nonlocal transverse Néel order, and the correlation length, respectively. It is found that all the critical exponents are varying continuously along the phase transition line δ=0, and the ratios of critical exponents imply that the phase transition is in conformity with the weak universality. The linear relations of the critical exponents are able to illustrate the dependence between the critical exponents and the Dzyaloshinskii–Moriya interaction.

Skyrmion crystal and spiral phases in centrosymmetric bilayer magnets with staggered Dzyaloshinskii-Moriya interaction

We theoretically study a stabilization mechanism of the skyrmion crystal in centrosymmetric magnets with a bilayer structure. We show that the interplay between a layer-dependent staggered Dzyaloshinskii-Moriya interaction that arises from the absence of local inversion symmetry and the interlayer exchange interaction gives rise to a plethora of multiple-$Q$ states including the skyrmion crystal with a quantized topological number. By performing the simulated annealing for the bilayer triangular-lattice model under an external magnetic field, we demonstrate that the skyrmion forms the triangular-shaped crystals with different helicities in each layer owing to the staggered Dzyaloshinskii-Moriya interaction. Although the relative positions of the skyrmion core in each layer are different depending on the sign of the interlayer exchange interactions, the skyrmion crystal phases robustly appear under both ferromagnetic and antiferromagnetic interlayer interactions. We also find another two triple-$Q$ states with a uniform scalar chirality but without a quantized topological number in the low- and high-field regions. Especially, the low-field triple-$Q$ state exhibits the opposite sign of the scalar chirality to the skyrmion crystal, which is not found in the single-layer system. Our results indicate that the lack of local inversion symmetry in the lattice structure is another key ingredient to induce topological spin textures in centrosymmetric magnets.

Low-Temperature Transport in the Xy Chain with Staggered Dzyaloshinskii-Moriya Interaction and Staggered External Field

Low-Temperature Transport in the Xy Chain with Staggered Dzyaloshinskii-Moriya Interaction and Staggered External Field

Spin-1/2 XY chain magnetoelectric: Effect of zigzag geometry

A spin-1/2 $XY$ chain model of magnetoelectrics on a zigzag chain is considered rigorously. The magnetoelectric coupling is described within the Katsura-Nagaosa-Balatsky mechanism. In the zigzag geometry it leads to the staggered Dzyaloshinskii-Moriya interaction. Using nonuniform spin rotations, the model is reduced to a dimerized $XY$ chain and solved exactly using the Jordan-Wigner transformation. We analyze the ground-state phase diagram of the model and the zero- and finite-temperature magnetoelectric effects and obtain the magnetization and polarization curves versus magnetic and electric fields, as well as the parameters of anisotropic dielectric and magnetoelectric response. It is also shown that the electric field may enhance the magnetocaloric effect in the model.

Degenerate and chiral states in the extended Heisenberg model on the kagome lattice

We present a study of the low temperature phases of the antiferromagnetic extended classical Heisenberg model in the kagome lattice, up to third nearest neighbors. First, we focus on the degenerate lines in the boundaries of the well-known staggered chiral phases. These boundaries have either semi-extensive or extensive degeneracy, and we discuss the partial selection of states by thermal fluctuations. Then, we study the model under an external magnetic field on these lines and in the staggered chiral phases. We pay particular attention to the highly frustrated point, where the three exchange couplings are equal. We show that this point can me mapped to a model with spin liquid behavior and non-zero chirality. Finally, we explore the effect of Dzyaloshinskii-Moriya (DM) interactions in two ways: an homogeneous and a staggered DM interaction. In both cases, there is a rich low temperature phase diagram, with different spontaneously broken symmetries and non trivial chiral phases.

Quantum phase transitions of a generalized compass chain with staggered Dzyaloshinskii–Moriya interaction

We consider a class of one-dimensional compass models with staggered Dzyaloshinskii–Moriya exchange interactions in an external transverse magnetic field. Based on the exact solution derived from Jordan–Wigner approach, we study the excitation gap, energy spectra, spin correlations and critical properties at phase transitions. We explore mutual effects of the staggered Dzyaloshinskii–Moriya interaction and the magnetic field on the energy spectra and the ground-state phase diagram. Thermodynamic quantities including the entropy and the specific heat are discussed, and their universal scalings at low temperature are demonstrated.

Skew information in the XY model with staggered Dzyaloshinskii-Moriya interaction

We study the performance of the lower bound of skew information in the vicinity of transition point for the anisotropic spin-1/2 XY chain with staggered Dzyaloshinskii-Moriya interaction by use of quantum renormalization-group method. For a fixed value of the Dzyaloshinskii-Moriya interaction, there are two saturated values for the lower bound of skew information corresponding to the spin-fluid and Néel phases, respectively. The scaling exponent of the lower bound of skew information closely relates to the correlation length of the model and the Dzyaloshinskii-Moriya interaction shifts the factorization point. Our results show that the lower bound of skew information can be a good candidate to detect the critical point of XY spin chain with staggered Dzyaloshinskii-Moriya interaction.

Renormalization-group approach to quantum Fisher information in an XY model with staggered Dzyaloshinskii-Moriya interaction

We investigate the quantum Fisher information and quantum phase transitions of an XY spin chain with staggered Dzyaloshinskii-Moriya interaction using the quantum renormalization-group method. The quantum Fisher information, its first-derivatives, and the finite-size scaling behaviors are rigorously calculated respectively. The singularity of the derivatives at the phase transition point as a function of lattice size is carefully discussed and it is revealed that the scaling exponent for quantum Fisher information at the critical point can be used to describe the correlation length of this model, addressing the substantial role of staggered Dzyaloshinskii-Moriya interaction in modulating quantum phase transitions.

Approach to control polarization and magnetic properties for multiferroics with Dzyaloshinskii-Moriya interaction

We propose a theoretical model for one-dimensional (charge transfer magnets with Dzyaloshinskii-Moriya (DM) interaction. By using Green's function theory, we have studied the effect of DM interaction on ferroelectric and magnetic properties, where ferroelectricity is induced through symmetric mechanism. It is shown that the uniform DM interaction reduces the polarization and makes the magnetization plateau narrow down. Moreover, the transition temperature descends as the uniform DM interaction ascends, which is attributed to the decrease of the energy gap. In addition, the staggered DM interaction, which is related to intersite distance, is also discussed. It is also found that there exists a critical point, above or below which the staggered DM interaction plays different roles on the polarization, transition temperature, and magnetic behavior. As the staggered DM interaction is larger, it enhances the polarization and transition temperature and meanwhile widens the magnetization plateau, otherwise it reduces the polarization, transition temperature, and magnetization plateau. The results provide approach to control the transition temperature and physical behavior of multiferroics.

Domain wall dynamics of the spin- $\frac{1}{2}$ Ising-like antiferromagnetic chain in presence of Dzyaloshinskii-Moriya interactions

We consider a one-dimensional Ising-like S = $\frac{1}{2}$ Heisenberg antiferromagnetic Hamiltonian and study the dynamics of domain wall excitations in presence of both uniform and staggered Dzyaloshinskii-Moriya interactions. We obtain dispersion relations and dynamical spin correlation functions, S x x (q, ω) using the basis of domain wall pair states. It is shown that the line shapes of S x x (q, ω) are highly asymmetric over the whole Brillouin zone such that the spectral weights mainly concentrate in the low energy side. It is observed that presence of staggered Dzyaloshinskii-Moriya interaction explains the experimental results on the Ising-like antiferromagnetic compounds CsCoCl3 and CsCoBr3 very well.

The symmetric and antisymmetric superexchange interactions in spin-Peierls system

The influences of Dzyaloshinskii–Moriya (DM) interaction and Kaplan–Shekhtman–Entinwohlman–Aharony (KSEA) interaction on the dimerization of a spin-Peierls system are investigated theoretically by using the Lanczos numerical method. The ground state of the spin-Peierls system is still dimerized phase when both of the DM and the KSEA interactions have the same value with Heisenberg interaction. It is found that the KSEA interaction and uniform DM interaction are always against systemic dimerization, but the staggered DM interaction acts in favour of dimerization. Furthermore, the influences of the DM and the KSEA interactions are also studied in terms of the ground state index rate and the energy gap index rate of the dimerized Heisenberg system. The results show that the DM interaction makes the index rates larger, while the KSEA interaction makes them smaller.

Breathers and Raman scattering in a two-leg ladder with staggered Dzyaloshinskii-Moriya interaction

Recent experiments have revealed the role of the staggered Dzyaloshinskii-Moriya interaction in the magnetized phase of an antiferromagnetic spin-$1∕2$ two-leg ladder compound under a uniform magnetic field. We derive a low-energy effective field theory describing a magnetized two-leg ladder with a weak staggered Dzyaloshinskii-Moriya interaction. This theory predicts the persistence of the spin gap in the magnetized phase, in contrast to standard two-leg ladders, and the presence of bound states in the excitation spectrum. Such bound states are observable in Raman scattering measurements. These results are then extended to intermediate Dzyaloshinskii-Moriya interaction using exact diagonalizations.

ESR study of the anisotropic exchange in the quasi-one-dimensional antiferromagnetSr2V3O9

The chainlike spin-$1/2$ antiferromagnetic vanadium oxide compound ${\mathrm{Sr}}_{2}{\mathrm{V}}_{3}{\mathrm{O}}_{9}$ is studied by electron spin resonance (ESR) with special attention to the space distribution of the Dzyaloshinskii-Moriya (DM) vector along magnetic chains. The angular variation and the temperature dependence of the ESR linewidth is measured in two different planes of a single crystal in the temperature range 4.2--500 K. The ESR data interpretation is based on the combined application of the standard ESR theory for low-dimensional systems and an updated theory using a hidden symmetry in the antiferromagnetic spin-$1/2$ chain model with the staggered DM interaction. As a result, a DM interaction with a more general (nonstaggered) spatial distribution of DM vectors is claimed to be responsible for the magnetic properties of the chainlike system ${\mathrm{Sr}}_{2}{\mathrm{V}}_{3}{\mathrm{O}}_{9}.$

Electron paramagnetic resonance with parallel pumping in quantum spin chains with field-induced spin gap

Recently several compounds were observed to reveal properties of a one-dimensional spin-$\frac{1}{2}$ antiferromagnetic Heisenberg chain with gapless low-lying spin excitations in an absence of an external magnetic field. However even a very weak external magnetic field yields an onset of a spin gap for those low-lying excitations. Usually this onset of a field-induced spin gap is related to the presence of a staggered Dzyaloshinskii-Moriya interaction, or to the staggered effective g factors of magnetic ions. Experiments on thermodynamic properties cannot distinguish between those two origins for the spin-gap formation. Here we propose the setup for an experiment, in which one can clearly distinguish between the staggered Dzyaloshinskii-Moriya coupling and staggered external magnetic field: an electronic paramagnetic resonance in the parallel pumping geometry. The characteristics of the system under conditions of such an experiment, i.e., the renormalization of the homogeneous and staggered magnetizations, power of the microwave magnetic field, absorbed by the system, are calculated. Several important features of the solution are discussed.