Abstract
Stefano sanvitos (Trinity College)
Quantitative quantum transport theory exploring topological materials and spin excitations
Quantitative electron transport theory has made enormous progresses in the last decade and today fully functional algorithms based the non-equilibrium Green's function (NEGF) formalism implemented within density functional theory (DFT) are the workhorse for modeling material-specific nano-devices . In this talk I will review the basics of the NEGF+DFT method and show a number of applications to real devices. Importantly as the NEGF can be implemented both with ab initio electronic structures, but also with simple non-interacting Hamiltonians, it is suitable to tackle complex problems of transport between materials with different electron properties and macroscopic orders. As an example of these I will present our recent work on the transport properties of hybrid junctions formed by a superconductor and a topological insulator, either conserving or violating time-reversal symmetry. In particular, I will discuss as doping with magnetic impurities has rather different consequences on the transport across such devices depending on the symmetries of the topological insulator. Finally I will discuss how our present formalism can be extended to describe non-elastic excitations and I will provide examples of spin-flip scattering.