报告人： Jun Yan 博士 （美国马里兰大学物理系）
时 间： 1月20日（周四），上午10：00
Graphene is the rising new star in the world of nanoelectronics. Since the first mechanical exfoliation and isolation of the material in 2004, its superior electronic, mechanical, and vibrational properties have attracted world-wide interest from the condensed matter science and engineering communities. In this talk, I will present our studies of graphene with Raman spectroscopy and electronic transport measurements. Light scattering of lattice vibration reveals intriguing phonon structures which are closely linked to the unique electronic bands of the Dirac fermions. We observed significant modulation of phonon renormalization  via tuning the charge density or changing the magnetic field of the electronic system. This leads to discoveries of phonon anomaly , breaking of inversion symmetry , and mode anti-crossing behaviors . In particular, the broken inversion symmetry creates a bandgap in bilayer graphene, which we investigate with a unique dual-gated Corbino-disk geometry . Our transport studies provide strong evidence that the gap opening is significant and is in good agreement with infrared spectroscopy.
 J. Yan et al., PRL 98, 166802 (2007).
 J. Yan et al., PRL 101, 136804 (2008).
 J. Yan et al., PRB 80, 241417(R) (2009).
 J. Yan et al., PRL 105, 227401 (2010).
 J. Yan and M. S. Fuhrer Nano Lett., 10, 4521 (2010).