arXiv subjects

Arghya Sil

Publications and source records attributed to Arghya Sil.

4 recordsLinked to original sources

arXiv2023

Topological phases of monolayer and bilayer depleted Lieb lattices

Existence of nontrivial topological phases in a tight binding Haldane-like model on the depleted Lieb lattice is reported. This two-band model is formulated by considering the nearest-neighbor, next-nearest-neighbor and next-next-nearest-neighbor hopping terms along with complex phase which breaks the time reversal symmetry of this semi-metallic system. Topological feature of this model is studied along with the presence of sublattice symmetry breaking staggered onsite energy. Combined effect of these two broken symmetries is found crucial for an additional transition between nontrivial and trivial phases. System exhibits two types of phase transitions, say, between two nontrivial phases and nontrivial to trivial phases. Nonzero Chern numbers, existence of Hall plateau and symmetry protected edge states confirm the presence of the nontrivial phases. This two-band system hosts four different types of phases where two are topological. Additionally topological properties of stacked bilayer of the depleted Lieb lattices is also studied with similar Haldane-like Hamiltonian. This four-band system is found to host Chern insulating phases, with higher values of Chern numbers supported by in-gap edge states.

cond-mat.mes-hall↗

arXiv2020

First and Second Order Topological Phases on Ferromagnetic Breathing Kagome Lattice

In this work, topological properties of a ferromagnetic Heisenberg model on a breathing kagome lattice are investigated extensively in the presence of Dzyaloshinskii-Moriya interaction. While the kagome ferromagnet hosts only a single first order topological phase, the breathing kagome system exhibits multiple first and second order topological phases along with their coexistence. Magnon dispersion relation is obtained by using linear spin wave theory. Flat band and Dirac cones are obtained in the absence of Dzyaloshinskii-Moriya interaction. A topological phase diagram is presented where several first and second order phases as well as their overlap are identified. Values of thermal Hall conductivity for all the first order phases are obtained. Distinct first order phases are characterized by different sets of Chern numbers in association with the necessary chiral edge states in accordance to the first order bulk-boundary-correspondence rule. Second order phase is characterized by polarization along with the emergence of corner states. Violation of the second order bulk-corner-correspondence rule has been noted in some regions.

cond-mat.str-el↗

arXiv2020

Emergence of photo-induced multiple topological phases on square octagon lattice

In this study, a tight-binding model on square octagon lattice with nearest-neighbour and next-nearest-neighbour hoppings is considered. The system is topologically trivial although it exhibits quadratic band-touching points in its band-structure. It is shown that the system drives towards topologically non-trivial phases as soon as it is exposed to monochromatic circularly polarized light. Multiple topological phases are found to emerge with the variation of amplitude of light. An effective time-independent Hamiltonian of the system is obtained following the Floquet-Bloch formulation. Quasi-energy band-structures along with definite values of Chern numbers for respective bands are obtained. Characterization of topological phases are made in terms of band structure and Chern numbers. In addition, Hall conductance and topologically protected chiral edge states are obtained to explain the topological properties. Density of states is obtained in every case. The system undergoes a series of topological phase transitions among various topological phases upon variations of both amplitude of light and hopping strengths. It exhibits Chern insulating and Chern semimetallic phases depending on the values of lattice filling.

cond-mat.mes-hall↗

arXiv2020

Non-trivial Topological Phases on the Stuffed Honeycomb Lattice

We report the appearance of nontrivial topological phases in a tight-binding model on the stuffed honeycomb lattice. The model contains nearest neighbor and next nearest neighbor hopping terms coupled with an additional phase depending on the direction of hopping. Chern insulating and semi-metallic phases emerge with the change of hopping parameters. Nonzero Chern numbers characterizing the bands and the existence of topologically protected edge states in the gap between the relevant bands confirm the presence of those phases. We show that adding an extra basis to Haldane's honeycomb model can lead to an additional topological phase characterized by Chern number $\pm2$. Transition between different topological phases driven by the hopping parameters has been illustrated in the topological phase diagram of the system. Zero temperature Hall conductivity along with density of states is evaluated. Topological properties of another tight-binding model on the stuffed square lattice are also reported in this article.

cond-mat.str-el↗