Scientific Calendar Event



Starts 9 Nov 2017 11:30
Ends 9 Nov 2017 12:30
Central European Time
ICTP
Leonardo Building - Luigi Stasi Seminar Room
The electronic structure of many devices where the two-dimensional gases are engineered can have degenerate valleys to be occupied by charge carriers. This feature for long has been seen as a drawback, but more recently, also owing to the discovery of graphene and monolayer group-VI transition metal dichalcogenides, it has been recognized as an opportunity to have an additional degree of freedom to manipulate the electrons beside the charge and the spin, leading to the so-called valleytronics. The valley degeneracy, that in a minimal description can be seen as an additional spin, has large impact on correlations in these systems and can enrich their phase diagram in general.

In this talk I will discuss how this additional degree of freedom affects two different systems. How valley polarization changes the magnetic response in AlAs quantum well once we take into account the mass anisotropy proper to this system and how results on spin-susceptibility, based on Quantum Monte Carlo simulations, compare with experimental findings. The other aspect that will be addressed is how the phase diagram of a symmetric electron-hole bilayer is modified once there is in-plane two-fold valley degeneracy. Results for this simple model can be relevant for the recent proposal to search for indirect excitons condensation in coupled graphene bilayers that, on a wide density range, have a quadratic energy dispersion.