报告题目：Dirac points, Valley States and Valley Edge States in phononic crystals

报 告 人：刘正猷教授

工作单位：武汉大学物理科学与技术学院

报告时间：2017年5月13日（周六）下午4:00

报告地点：博逸楼401会议室

内容简介：

 Phononic crystals are artificial periodical structures with energy bands for sound in momentum space. Dirac conic dispersions can be realized at the Brillouin zone corners of the crystals with hexagonal lattice. By reducing the symmetry of the crystals, the degeneracy at Dirac point can be lifted and a bandgap opens, resulting in two inequivalent valleys with opposite vortex. The valley vortex states which carry angular momentum can exert torque on particles dispersed in the fields.  Breaking system symmetry in opposite ways leads to phononic crystals with inverse band gap, and when they are put together, topological one-way edge states emerge on the interfaces.

个人简历：

Professor Zhengyou Liu received the B. Sc., M. Sc. and Ph. D degrees in physics from Wuhan University in 1986, 1989, and 1993 respectively. He has been a professor in Wuhan University under the Cheung Kong Scholars Programme of the Ministry of Education of China since 2001. He is the recipients of the China National Funds for Distinguished Young Scientists in 2004, the State Natural Science Prize of the 2nd grade in China in 2010, and the Brillouin Medal by the International Society of Phononics in 2015. He has worked on the theories on quasicrystals, phononic/photonic crystals and metamaterials, and the interaction of waves or fields with particles. He has published more than 150 peer reviewed papers, including 11 PRL, 1 Science, 1 Nature Physics, 1 Adv. Mat., with over 8300 Google Scholars citations and H-index = 42.

刘正猷，武汉大学物理科学与技术学院教授，博士生导师。国家杰出青年基金获得者，教育部长江学者特聘教授，国家新世纪百千万人才工程国家级入选者，曾荣获国家自然科学奖二等奖（第一完成人）。现兼任国务院学位委员会学科评议组成员。