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    제목 Mott-Hall Insulator and Chiral Spin Liquid Phase in Neutral Graphene in a Magnetic Field (Mott-Hall Insulator and Chiral Spin Liquid Phase in Neutral Graphene in a Magnetic Field)
    TYPE Distinguished Lectures
    DATE/TIME 2009-12-02 ~ 2009-12-02
    PLACE APCTP Seminar Room (APCTP Seminar Room)
    SPEAKER Prof. Ganapathy Baskaran (Prof. Ganapathy Baskaran)
    AFFILIATION Institute of Mathematical Sciences (Institute of Mathematical Sciences)

    * 행사명 : Mott-Hall Insulator and Chiral Spin Liquid Phase in Neutral Graphene in a Magnetic Field

    * 연   사: Prof. Ganapathy Baskaran (Institute of Mathematical Sciences)

    * 일   시: Dec. 2 (Wed) 16:30

    * 장   소: #512, Hogil Kim Memorial Bldg., POSTECH



    * Title : Mott-Hall Insulator and Chiral Spin Liquid Phase in Neutral Graphene in a Magnetic Field

    * Speaker: Prof. Ganapathy Baskaran (Institute of Mathematical Sciences)

    * Date & Time: Dec. 2 (Wed) 16:30

    * Place: #512, Hogil Kim Memorial Bldg., POSTECH

    * Abstract:

    Neutral graphene in a magnetic field exhibits an unexpected insulating phase and a missing quantum Hall plateau. Electrons in graphene in a magnetic field has $2N_B$ fold degenerate n = 0 single particle Landau levels from two valleys and exactly $2N_B$ spinful electrons. Here $N_B$ is the number of elementary magnetic flux quanta threading the sample. We develop a microscopic theory where, at low energy scales, a complete set of $2N_B$ single particle Landau-Gaussian orbitals forming a exit{Von Neuman lattice} have single electron occupancy and dangling spins. Certain novel superexchange interaction among spins destabilise the exchange induced quantum Hall ferromagnetism, decouple spin from charge and organize spins into a chiral spin liquid state. Charged excitations have a Mott gap and spin excitations are either gapless or have a smaller gap. Spin charge separation removes edge channels for spinful electrons and prevents Hall plateau formation.


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