[PAST EVENT] Martin Alexander Rodriguez Vega, Physics - Oral Exam for the Ph.D.

May 13, 2016
10am - 1pm
Small Hall, Room 122
300 Ukrop Way
Williamsburg, VA 23185Map this location
Abstract: In this dissertation, we study theoretically heterostructures based on Dirac materials, i.e. materials, such as graphene in which the electrons behave as massless Dirac fermions at low energies.

We first examine how the presence of long-range disorder affects the electronic ground state of a double layer graphene heterostructure formed by two graphene layers separated by a thin dielectric film. We then identify the necessary conditions for the formation of an interlayer exciton condensate in such a system. We also comment on the effect of long-range disorder on the broken symmetry ground state induced by electron-electron interactions in bilayer graphene.

Then, we study the transport properties of heterostructures obtained by stacking a graphene layer on the surface of a strong three-dimensional topological insulator (TI). In particular, we determine the non-equilibrium current-induced spin density accumulation for these systems using linear response theory and taking into account the effects of long- and short-range disorder both in the limit of strong and weak tunneling between the graphene layer and the TI.

Finally, using some of the theoretical approaches developed to characterize the effect of long-range disorder in Dirac materials, we study the effect of long-range inhomogeneities in first-order phase transitions. In particular, we present a theoretical model to describe the effect of inhomogeneities on the relaxation dynamics of vanadium dioxide films after a photo-induced metal-insulator transition.

Bio: Martin is a physics student from Colima, Mexico. He earned his Bachelor of Science at the Universidad de Colima, Mexico in 2011. After that, he started his graduate studies at William & Mary working on condensed matter physics under the supervision of Professor Enrico Rossi. His dissertation focuses on the study of disorder effects in Dirac heterostructures. After graduation, he will work as a postdoc in the condensed matter theory group at Indiana University.