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The property of matter-wave vector solitons in a spin-1 Bose-Einstein condensate with spin-orbit and Zeeman couplings is investigated by multiscale perturbation method. The excitation spectrum and the corresponding state vectors of the system are obtained analytically, and they can be adjusted by the parameters of the system. The bright and dark vector solitons are formulated by reducing the three-component coupled Gross-Pitaeviskii equations to a standard nonlinear Schrödinger equation, which has the solutions of the bright and dark solitons with positive or negative mass depending on the product of the effective dispersive and nonlinear coefficients. The moving vector solitons are demonstrated by adjusting specific momentum near the energy minimum. Finally, the magnetized features of the vector solitons are discussed by the spin polarization of the system. • The excitation spectrum for the vector solitons, determined by the parameters of the system, is obtained analytically. • The analytical bright and dark vector solitons are formulated and the moving solitons are demonstrated by adjusting specific momentum. • The solitons with positive or negative mass depending on the product of the effective dispersive and nonlinear coefficients are analyzed. • The magnetized features affected by spin-orbit and Zeeman couplings are discussed by the spin polarization of the system. [ABSTRACT FROM AUTHOR]

We investigate the ground states of an antiferromagnetic spin-1 Bose–Einstein condensate with spin–orbit coupling in a concentrically coupled toroidal trap. A new necklace-type state with double-ring structure is created in the system due to the spin–orbit coupling. The petal number of the necklace state is increased with enhancing the strength of the spin–orbit coupling. When the rotation is introduced, the condensate can be dragged into the outer trough of the trap by increasing the rotation frequency, which makes it possible to realize the exotic ground state combined by the necklace state at the inner trough and the persistent flow at the outer one. Once the two troughs of the toroidal trap are populated by the persistent flow at the specific effective interactions between atoms, the hidden vortices may occur in the central region of the trap and at the barrier between the two troughs. In addition, the visible vortex with the laminar structure can be generated under the more effective atomic interaction. [ABSTRACT FROM AUTHOR]

Abstract: The head-on collisions of two ring dark solitons in inhomogeneous Bose–Einstein condensates (BECs) with thin disk-shaped potential are studied by the extended Poincaré–Lighthill–Kuo (PLK) perturbation method. The result shows that the system admits a solution with two concentric ring solitons, one moving inwards and the other moving outwards, which in small-amplitude limit, are described by two modified cylindrical KdV equations in the respective reference frames. In particular, the analytical phase shifts induced by the head-on collisions between two ring dark solitary waves are derived, and the result shows that the phase shifts change with the radial coordinate r according to the law (where ), which are quite different with the homogeneous case. [Copyright &y& Elsevier]

Abstract: The evolution of Bose–Einstein condensates (BECs) loaded into a periodic ring optical lattices (OL) trap is studied. By means of the variational method and direct numerical simulations of the Gross–Pitaevskii (GP) equation, the ground state properties and the vortex stabilities of the condensates for both repulsive and attractive cases are investigated. The results show that the bound states exist for determinate OL strength and interatomic interaction. However, the ground states of BECs undergo delocalizing–localizing transition for both attractive and repulsive cases as the strength of the OL or the interatomic interaction is decreased below the critical value. The ring OL can suppress the delocalizing transition efficiently. [Copyright &y& Elsevier]

The antiferromagnetic-semiconductor extreme tensile strain (8%) states of La 0.7 Ca 0.3 MnO 3 membranes was achieved by Hong et al. (2020) [23]. To understand such tunable magnetic and electronic properties in these La 2 3 M 1 3 MnO 3 (M=Ca, Sr) systems, we have investigated the magnetic and electronic behaviors of La 2 3 M 1 3 MnO 3 (M=Ca, Sr) under strain and charge doping using first-principles calculations. A ferromagnetic-semiconductor phase is predicted for La 2 3 Sr 1 3 MnO 3 beyond 4% biaxial tensile strain. Meanwhile, its energy gap and magnetic anisotropic energy increase as the strain increases. We also discover that the change of magnetic exchange energy in La 2 3 Ca 1 3 MnO 3 under charge doping is in analogy to the scenario directly changing the Ca concentrations. Based on the magnetic competition analysis, it is expected that the carrier concentration and strains dominate the magnetic ground state while the La/Ca distributions have little impact. The highly tunable magnetic-electronic properties offer opportunities for the future magnetic-electronic materials design and applications. • DFT SCAN calculations give excellent structure and magnetic moments of the studied systems. • A ferromagnetic semiconductor is predicted for La 2/3 Sr 1/3 MnO 3 under biaxial tensile strain. • Carrier concentration combined with strains dominate the magnetic coupling. • Magnetic anisotropic energy is enhanced by 30 μeV by strains for La 2/3 Sr 1/3 MnO 3. [ABSTRACT FROM AUTHOR]

Abstract: We explore the transmission through a time-periodic potential barriers in single layer graphene with an induced energy gap in this work. The analytical solutions of the transmission probabilities for the central band and the first sidebands are obtained. The transmission probabilities as the function of the induced energy gap and the incidence electron energy are discussed. We also investigate how critical angles change as the induced energy gap and incidence electron energy. The study of transmission properties will benefit applications in graphene-based nano-electronics. [Copyright &y& Elsevier]

We investigate the discrete nonlinear Schrödinger model with helicoidal hopping and a power-law nonlinearity, motivated by the tunable nonlinearity in the model of DNA chain and ultra-cold atoms trapped in a helix-shaped optical trap. In the study of modulational instability, we find a successive destabilization along with increasing nonlinear-power. In particular, the critical amplitudes of second-stage instability decrease as nonlinear-power increases. Furthermore, it is shown that information on the stability properties of weakly localized solutions can be inferred from the plane-wave modulational instability results. This link enable us to analytically estimate the critical parameters at which the breather solutions turn unstable, and find these parameters are dramatically influenced by the nonlinear-power. The stability properties of localized breathers perform an obvious change when the nonlinear power crosses a critical value γ c r . It is reflected that at weak nonlinearity the breathers exhibit monostability, while exceeding γ c r the bistability and instability will set in. The interplay between nonlinear-power and long-range hopping on the stability properties of breathers is also discussed in detail. [ABSTRACT FROM AUTHOR]

• Novel ginkgo-leaf spectrum is reported in cold atomic systems. • Triple degeneracy points and degeneracy line of nonlinear spectrum are predicted. • That the band curvature and current density can be controlled by interaction is proved. Band structure is an important tool to characterize the physical properties of periodic systems. In this work, we investigate the nonlinear spectrum and current density in cold atoms with interaction-dependent dispersion (IDD). The results reveal that IDD causes the nonlinear loop structure, which means that the dynamical stability is destroyed, resulting in the loss of superfluidity. More interestingly, the repulsive IDD induces a more complex deformation of spectrum. Different from the previous studies, the conversion between positive and negative curvature loop structures appears in the system. Furthermore, there will be a pair of triple degeneracy points on the lower band (n = 2 n c) and a double degeneracy line between them, which will uncover new physical properties, e.g., nonlinear Landau-Zener tunneling. Since the nonlinear interaction of cold atoms is highly controllable through Feshbach resonance, this fascinating phenomenon is expected to be realized in cold atomic systems in the near future. [ABSTRACT FROM AUTHOR]