Abstract:

This talk is divided into two parts. In the first part of this talk, I will introduce our study on electron-spin to phonon coupling in graphene decorated with heavy adatoms. Using group theory and a tight-binding model, the coupling between the low-energy in-plane phonons and the electron spin is investigated. In order to quantify the effect of the coupling to the lattice on the electronic spin dynamics, we compute the spin-flip rate of electrons and holes. We show that the latter exhibits a strong dependence on the quasi-particle energy and system temperature. Our results provide the foundation for future investigations of spin transport and superconductivity in this system.

In the second part, I will present a theoretical study on unconventional Bose-Einstein condensations of two-species mixture in the p-orbital bands. Different from the single-species case, the two-species boson mixture exhibits two non-equivalent complex BECs in the intraspecies-interaction-dominating regime, with one breaking time-reversal symmetry while the other not. When the interspecies interaction is tuned across the SU(2) invariant point, the system undergoes a quantum phase transition toward a real-valued checkerboard state characterized by a staggered spin density structure. An experimental scheme for phase measurement is presented.

[1] Jhih-Shih You, Daw-Wei Wang and Miguel A. Cazalilla, Phys. Rev. B 92, 035421 (2015)

[2] Jhih-Shih You, I-Kang Liu, Daw-Wei Wang, Shih-Chuan Gou and Congjun Wu, arXiv:1508.02914