学术报告（6月23日）

主持人：姚道新 教授

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摘要：
In Graphene and topological insulators (recently also in Weyl semimetals), the Hamiltonian is governed by Dirac equation. In spintronics the Hamiltonian is similar but with the strength of Fermi velocity to be much smaller, making the system cross over from Dirac fermions to Schrodinger fermions. Strong distortion of the Fermi surface could introduce a hexagonal warping term in the Hamiltonian in which the energy is proportional to the cubic of the momentum. Optical and magneto-optical measurements play an important rule in determining the physics of superconductors and now we use these tools to probe topological materials. Finally the impact of electron-phonon interaction on these systems will be addressed.