Tuesday, 12 June, 2012
Group Seminar MPQ: Topological insulators in optical lattices: interaction and trapping effects.
Tuesday, 12.06.2012 10:00 a.m. (s.t.) in Herbert-Walther-lecture room, MPQ Garching
Michael Buchhold, Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, Frankfurt
Topological insulators have come to forefront of condensed matter research
with the discovery of time-reversal invariant couplings that open bulk gaps in
materials, but retain conduction states on the edges.
With the ability to create
artificial gauge fields in ultracold gases, these systems can now be
realized in highly tunable experiments to probe the behaviour of these interesting
phases of matter. However, ultracold gases have intrinsic differences to solid-state
materials, such as the relatively small size of the system and the presence of a
trapping potential, which must be clearly understood both theoretically and
in how observations may be performed in experiment.
I will discuss the effects of interaction, disorder and trapping on a
particular system that is of interest: the spinful extension of the Hofstadter model,
that exhibits topologically insulating, quantum spin-hall phases in an optical
lattice with square geometry using both real-space dynami- cal mean-field
theory and analytical techniques. The tunability of this system allows for a large
degree of freedom, and by adjusting the size of the magnetic unit cell,
along with the strength of Rashba spin-orbit coupling and a staggered
super-lattice potential, many topologically non-trivial regions have been identified.