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The study of the Heisenberg-Kitaev honeycomb ferromagnets has recently drawn attention because of their rich topological properties. Topological phase transitions may arise when there exist two or more distinct topological phases, and they are often revealed by a gap-closing phenomenon. In this work, we investigate the magnonic properties of honeycomb ferromagnets exhibiting Kitaev and DMI interactions in the presence of a Heisenberg exchange and magnetocrystalline anisotropy exposed to a magnetic field. We employ the Self-Consistent Renormalization (SCR) spin wave theory to investigate the effects of magnon-magnon interactions (MMIs) and thermal fluctuations on the properties of magnons. Our findings demonstrate that the magnon system undergoes topological phase transitions driven by temperature and magnetic fields, which are attributed to MMIs. Specifically, as the temperature rises, the magnon band gap at the Dirac points closes and reopens at the critical temperature Tc , which is below the Curie temperature. By showing that the Chern numbers of the magnonic bands are distinct above and below Tc , we confirm that the gap-closing phenomenon is indeed a signature for the topological phase transitions. Furthermore, our analysis indicates that the thermal Hall conductivity in the magnonic system exhibits a sign reversal at Tc , which can serve as an experimental probe of its topological nature.

Dynamics of neutral test particles in the spacetime of a Bardeen AdS black hole surrounded by quintessence dark energy is studied. First, we analyze the properties of the black hole and possible values of the monopole charge and quintessential parameters that allows the existence of the event horizon. The effects of the parameters on the effective potential and the innermost stable circular orbit radius are also studied. For the neutral test particles motion, it is shown that as the quintessential parameters increase, the radius of ISCO be increased. We have analyzed the dynamical behaviors of the neutral test particles by applying techniques including Poincar'e sections, power density and bifurcation diagram. It is shown that the presence of a quintessence parameter creates the chaotic phenomenon for the motion of neutral particle in a Bardeen AdS black hole spacetime. The amplification of chaos typically occurs as the energy increases under appropriate circumstances., Comment: arXiv admin note: text overlap with arXiv:1605.09506 by other authors

The photoinduced topological phase transitions and thermal Hall conductivity of a kagome magnet with Heisenberg, Kitaev, and DM interactions under an external magnetic field aligned along the [111] directions is investigated in this study. In the presence of a strong magnetic field perpendicular to the lattice plane in the [111] direction, the system exhibits a fully polarized paramagnetic phase and the magnon band carries an asymmetric Chern number across the phase diagram region. Utilizing magnetic Floquet-Bloch theory, we demonstrate that periodically driven intrinsic topological magnetic materials can be manipulated into different topological phases with varying Berry curvature, Chern numbers and thermal Hall conductivities signatures by adjusting light intensity throughout the phase diagram region., Comment: arXiv admin note: text overlap with arXiv:1801.04932 by other authors

When a Heisenberg honeycomb ferromagnet is irradiated by high frequency circularly polarized light, the underlying uncharged magnons acquire a time dependent Aharonov Casher phase, which makes it a Floquet topological magnon insulator. In this context, we investigate the many body interaction effects of Floquet magnons in laser irradiated Heisenberg honeycomb ferromagnets with ocontaining Dzyaloshinskii Moriya interaction under the application of circularly polarized off resonant light. We demonstrate that the quantum ferromagnet systems periodically laser driven exhibits temperature driven topological phase transitions due to Floquet magnon magnon interactions. The thermal Hall effect of Floquet magnons serves as a prominent signature for detecting these many body effects near the critical point, enabling experimental investigation into this phenomenon. Our study complements the lack of previous theoretical works that the topological phase transition of the Floquet magnon under the linear spin wave approximation is only tunable by the light field. Our study presents a novel approach for constructing Floquet topological phases in periodically driven quantum magnet systems that goes beyond the limitations of the linear spin wave theory. We provide numerical results based on the well known van der Waals quantum magnet CrX3 (X=F, Cl, Br, and I), calling for experimental implementation.

We theoretically study topological properties of Floquet magnon in a laser-irradiated Kitaev-Heisenberg honeycomb ferromagnet with the Dzyaloshinskii-Moriya interaction by means of the Floquet-Bloch theory. It is found that the Kitaev-Heisenberg ferromagnet can reveal two topological phases with different Chern numbers when it is irradiated by a circular-polarized light laser. Our results show that the topological phase of the system can be switched from one topological phase to another one via varying the light intensity. The intrinsic DMI plays a crucial role in the occurrence of photoinduced topological phase transition. It is shown that the sign reversal of the thermal hall conductivity is an important indicator on photoinduced topological phase transitions in the Kitaev-Heisenberg honeycomb ferromagnet.

This work is devoted to studying the magnon-magnon interaction effect in a two-dimensional checkerboard ferromagnet with the Dzyaloshinskii-Moriya interaction. By means of the first-order Green function formalism, the influence of magnon-magnon interaction on the magnon band topology is analyzed. In order to verify that the gap-closing phenomenon is a signature for the topological phase transitions of the checkerboard ferromagnet, we display that the Chern numbers of renormalized magnon bands are distinct above and below the critical temperature. Our results show that the checkerboard ferromagnet possesses two topological phases and its topological phase can be controlled either by the temperature or applied magnetic field due to magnon-magnon interactions. Interestingly, we find that the topological phase transition occurs twice with the increase of the temperature, which is different from the result of the honeycomb ferromagnet., Comment: arXiv admin note: text overlap with arXiv:2306.02505

This theoretical research is devoted to study topological phase transitions in a two-dimensional honeycomb ferromagnetic lattice with unequal Dzyaloshinskii-Moriya interactions for the two sublattices. With the help of a first-order Green function formalism, we analyze the influence of magnon-magnon interaction on the magnon band topology. It is found that the existence of the antichiral Dzyaloshinskii-Moriya interaction can led to a tilting of the renormalized magnon bands near the Dirac momenta. Then, the renormalized magnon band gaps at Dirac points have different widths. Through changing the temperature, we can observe the renormalized magnon band gap closing-reopening phenomenon, which corresponds to the topological phase transition. Our results show that the critical temperature of the topological phase transition is related to the strength of the antichiral Dzyaloshinskii-Moriya interaction., Comment: 20 papes

We investigate the circular motion and chaos bound of a charged particle near 4D charged AdS black holes in Einstein-Gauss-Bonnet gravity theory. By means of the Jacobian matrix, the analytical form of the Lyapunov exponent of the charged particle is constructed, which satisfies the upper bound when it is on the event horizon. By further expanding the Lyapunov exponent near the horizon and investigating a 4D charged Einstein-Gauss-Bonnet-AdS black hole with different Gauss-Bonnet coupling constant, we find that it has some specific values to determine whether a violation of chaos bound. Besides, we find that in contrast to the static equilibrium, the circular motion of charged particle can have a larger Lyapunov exponent due to the existence of angular momentum. Moreover, we show that the black hole gets closer to the extremal state as the Gauss-Bonnet coupling constant increases, and the bound is more easily violated. In addition, the range of particle charge that may violate the chaotic bound are found for different Gauss-Bonnet coupling constants. The results show that as the GB coupling parameter increases, the value of particle charge required to satisfy the violation of the chaos bound is even smaller.

We study the motion of a ring string in the background of the Bardeen-AdS black hole surrounded by the quintessence dark energy. The effects of the magnetic monopole charge, the quintessence state parameter, and the quintessence normalization parameter on the dynamical behavior of the ring string are respectively analyzed. Our numerical results show that the chaotic behavior of string generally becomes stronger with the increase of the quintessence normalization parameter. In particular, the conditions for the existence of chaos are distinctly diverse for two different quintessence state parameters. Furthermore, it is found that the magnetic charge does not significantly affect the chaotic behavior of the string in a specific range.

An analytical work on intrinsic localized modes in a two-dimensional Heisenberg ferromagnet on the checkerboard lattice is presented. Taking advantage of an asymptotic method, the governing lattice dynamical equations are reduced to one (2+1) -dimensional nonlinear Schr\"odinger. In our work, we obtain two types of nonlinear localized mode solutions, namely, Brillouin zone center modes and Brillouin zone corner modes. The occurrence conditions for these intrinsic localized modes are given in detail. Especially, we find that the competition between the Dzialozinskii-Moriy interaction and the next-nearest neighbor interaction of the checkerboard ferromagnet has an effect on the local structure of the Brillouin zone corner acoustic mode.

This theoretical work is devoted to investigating laser-irradiated Floquet topological magnon insulators on a two-dimensional checkerboard ferromagnet and corresponding topological phase transitions. It is shown that the checkerboard Floquet topological magnon insulator is able to be transformed from a topological magnon insulator into another one possessing various Berry curvatures and Chern numbers by changing the light intensity. Especially, we also show that both Tamm-like and topologically protected Floquet magnon edge states can exist when a nontrivial gap opens. In addition, our results display that the sign of the Floquet thermal Hall conductivity is also tunable via varying the light intensity of the laser field., Comment: This paper has been published in Physica Letter A

Based on the Melnikov method, we investigate chaotic behaviors in the extended thermodynamic phase space for a slowly rotating Kerr-AdS black hole under temporal and spatial perturbations. Our results show that the temporal perturbation coming from a thermal quench of the spinodal region in the phase diagram may cause the temporal chaos only when the perturbation amplitude is above a critical value, which involves the angular momentum . Under the spatial perturbation, however, it is found that the spatial chaos always occurs, which is independent of the perturbation amplitude., Comment: To be published in Chinese Physics C

We theoretically investigate nonlinear localized excitations in a Heisenberg honeycomb ferromagnet with a second neighbour Dzialozinskii-Moriya interaction, which has been proved to possess the topological band structure. Using the time-dependent variational principle, we obtain the equation of motion for the system in the Glauber coherent-state representation. By means of the semidiscrete multiple-scale method, different types of nonlinear localized excitations are gotten.Our results show that both two-dimensional discrete breathers and bulk gap solitons may occur in the Heisenberg honeycomb ferromagnet., Comment: This paper has been published in Journal of Magnetism and Magnetic Materials