Transport phenomena in nontrivial topological materials
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Date
2023
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Abstract
In this Ph.D. thesis, we present our work related to electronic quantum transport in materials with nontrivial topology. The fundamental objectives of our work were as follows: Firstly, to study ballistic transport in a nano junction made of a Type I Weyl semimetal material that contains a cylindrical defect created by the application of mechanical strain. In addition to the torsion effect modeled by a pseudo-gauge field, we added an external magnetic field and the repulsive effect of the deformation produced by the mismatch of the crystal lattice. Using the appropriate Landauer ballistic formalism to describe this type of system, we calculated their transport coefficients. Secondly, to study diffusive transport using the linear response regime, of a uniform and diluted concentration of the aforementioned defects through the bulk of a Weyl semimetal slab. For this purpose, we used the standard particle scattering theory, along with Green's functions techniques and diagrammatic methods. Finally, to study the diffusive transport through a single-layer graphene sheet doped with charged impurities, and influenced by the electromagnetic coupling to a topological insulator or a semiconductor. We pursued to investigate the role played by the magneto-electric effect produced by the topological insulator in transport properties, such as electrical conductivity. Here, we also applied a combination of methods based on scattering, linear response, Green's functions, and diagrammatics. We have obtained analytical expressions for the electrical and thermal conductivities, as well as for the Seebeck coefficient. Our results demonstrate the promising nature of these novel topological materials as thermoelectrics for future applications.
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Tesis (Ph.D. degree in Physics)--Pontificia Universidad Católica de Chile, 2023