Turkish Journal of Physics
Abstract
Electronic band structure of low dimensional materials significantly impacts their thermoelectric performance. A Mexican hat-like band structure, characterized by a ring-shaped extremum in momentum space, offers distinct advantages due to its singularity in the density of states at the band edge and its ability to enhance energy-dependent transport. This work investigates a two-dimensional tight-binding model hamiltonian that incorporates both nearest-neighbor (t1) and next-nearest-neighbor (t2) hopping. The ratio of the hopping amplitudes, ξ = t2/t1, serves as a tunable parameter that modulates the shape and depth of the Mexican hat dispersion. We use an analytical expression for the energy band of the form ε(k) = εv − α(k2 − k2 c)2, and demonstrate how the curvature α, the radius of the Fermi ring kc, and the valley height ε0 evolve with ξ. Using the Landauer formalism within the constant relaxation time approximation, we compute various properties, including the energy surface, band structures, density of states, transmission spectra, transport moments (L0, L1, L2), and thermoelectric properties such as electrical conductivity (σ), Seebeck coefficient (S), electronic thermal conductivity (κel), power factor (PF), and figure of merit (ZT ) as functions of the chemical potential at room temperature. Additionally, we evaluate PF and ZT as functions of temperature. Our results indicate that increasing ξ sharpens the density of states near the band edge, enhances the Seebeck coefficient, and improves the overall thermoelectric response. These findings emphasize the significance of band engineering by modulating hopping parameters as a viable strategy for optimizing next-generation thermoelectric materials.
DOI
10.55730/1300-0101.2782
Keywords
Thermoelectric, figure of merit, Mexican hat band structure
First Page
159
Last Page
168
Publisher
The Scientific and Technological Research Council of Türkiye (TÜBİTAK)
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
HILAL, M, & GÜLSEREN, O (2025). Implications of Mexican hat-like band structure on thermoelectric properties. Turkish Journal of Physics 49 (4): 159-168. https://doi.org/10.55730/1300-0101.2782
