Topological transition of graphene from quantum Hall metal to quantum Hall insul

Speaker             Prof.  X. R. Wang
Affiliation  Physics Department, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong SAR, China
Short CV
XIANG RONG WANG (王向荣)
EDUCATION: Ph.D. OF PHYSICS, July 1990, University of Rochester, MASTER OF ARTS, May 1986,University of Rochester, BACHELOR OF ARTS, July 1984, Wuhan University, PRC
EXPERIENCE:
    PROFESSOR, 7/09-present, Physics Department, HKUST
    ASSOCIATE PROFESSOR, 1/01-6/09, Physics Department, HKUST
    ASSISTANT PROFESSOR, 8/92-12/00, Physics Department, HKUST
    RESEARCH ASSOCIATE, 9/90-7/92, University of Minnesota
    RESEARCH ASSISTANT, 1/87-8/90, Phys. Dept., U. of Rochester
HONORS:     
    Minnesota Supercomputer Institute Fellow, 1991
    CUSPEA Selectee, China-United States, 1984
RESEARCH FIELD: Condensed Matter Theory and Statistical Physics

TELEPHONE: (852)2358-7488        E-MAIL: phxwan@usthk.ust.hk

Abstract
In this talk, I will present a theory for the recently observed insulating phase of graphene at charge neutrality point in high magnetic field quantum Hall (QH) experiments. We show that the magnetic field driven Peierls-type lattice distortion (due to the Landau level degeneracy) and random bond fluctuations compete with each other, resulting in a transition from a QH-metal state at relative low field to a QH-insulator state at high enough field at the charge neutrality point. The critical field that separates QH-metal from QH-insulator depends on the bond fluctuation. The picture explains well why the field required for observing the insulating phase is lower for a cleaner sample.

时间          2010年9月17日 星期五 下午16:00
地点    四川大学望江校区东区 物理馆 三楼阶梯教室(323室)
四川大学物理科学与技术学院 理论物理研究中心