Speaker: Zhao Liu

Beijing Computational Science Research Center    

Abstract: "Fractional Chern insulators" (FCI) is a very hot topic that has attracted much interest since June 2011 when the first three papers were published by PRL at the same time. FCI states are intriguing novel strongly-correlated states due to interactions between particles in nearly-flat bands with nonzero Chern number. The whole development of FCI can be divided into two tides. In the first tide, people focused on constructing lattice models whose energy bands have Chern number |C|=1 and searching possible FCI states in such bands. Those FCI states are usually considered as lattice versions of famous fractional quantum Hall (FQH) states and those discoveries open a possible realization of quantum Hall phenomenon in lattices and at room temperatures (at least in principle). In the second tide, people begun to consider lattice models with |C|=N>1 bands. Some FCI states in such higher Chern number bands were discovered but are not understood so far. (It's possible that they don't have counterparts of FQH states.) When will the third tide come? Let's see.

In this talk, I will give a brief introduction of FCI, mainly including
(1) The FCI states that have been discovered in |C|=1 bands as the lattice analogues of FQH states;
(2) The wavefunctions of FCI states in |C|=1 bands;
(3) The FCI states in higher Chern number bands.

These contents are based on my works on FCI:
(1) A. M. Läuchli, Z. Liu, E. J. Bergholtz, and R. Mössner, arXiv: 1207.6094, submitted to PRL.
(2) Z. Liu and Emil. J. Bergholtz, arXiv: 1209.5310, submitted to PRB.
(3) Z. Liu, E. J. Bergholtz, H. Fan, and A. M. Läuchli, arXiv: 1206.3759, accepted by PRL.

Date&Time: October 18, 2012 (Thursday), 14:30–15:30
Location: 606 Conference Room