Magnetic phases of XY model with three-spin terms: interplay of topology and entanglement.

Magnetic and topological properties along with quantum correlations in terms of several entanglement measures have been investigated for an antiferromagnetic (AFM) spin-1/2 XY model in the presence of transverse magnetic field and XZX-YZY type of three-spin interactions. Symmetries of the spin Hamiltonian have been identified. Under the Jordan-Wigner transformation, the spin Hamiltonian converted into spinless superconducting model with nearest neighbor (NN) hopping and Cooper pairing terms in addition to next NN Cooper pairing potential. Long range AFM order has been studied in terms of staggered spin-spin correlation functions, while the topological orders have been characterized by winding numbers. Magnetic and topological phase diagrams have been prepared. Faithful coexistence of magnetic and topological superconducting phases is found in the entire parameter regime. Boundaries of various quantum phases have been marked and positions of bicritical points have been identified.

Engineering topological phases of any winding and Chern numbers in extended Su-Schrieffer-Heeger models.

Simple route of engineering topological phases for any desired value of winding and Chern numbers is found in the Su-Schrieffer-Heeger (SSH) model by adding a further neighbor hopping term of varying distances. It is known that the standard SSH model yields a single topological phase with winding number,ν = 1. In this study it is shown that how one can generate topological phases with any values of winding numbers, for examples,ν=±1,±2,±3,…,in the presence of a single further neighbor term which preserves inversion, particle-hole and chiral symmetries. Quench dynamics of the topological and trivial phases are studied in the presence of a specific nonlinear term. Another version of SSH model with additional modulating nearest neighbor and next-nearest-neighbor hopping parameters was introduced before which exhibit a single topological phase characterized by Chern number,C=±1. Standard form of inversion, particle-hole and chiral symmetries are broken in this model. Here this model has been studied in the presence of several types of parametrization among which, for a special case the system is found to yield a series of phases with Chern numbers,C=±1,±2,±3,….In another parametrization, multiple crossings within the edge states energy lines are found in both trivial and topological phases. Topological phase diagrams are drawn for every case. Emergence of spurious topological phases is also reported.