1109.5955 (Jörn W. F. Venderbos et al.)

Fractional quantum-Hall liquid spontaneously generated by strongly
correlated t_2g electrons    [PDF]

Jörn W. F. Venderbos, Stefanos Kourtis, Jeroen van den Brink, Maria Daghofer

For topologically nontrivial and very narrow bands, Coulomb repulsion between
electrons has been predicted to give rise to a spontaneous fractional
quantum-Hall (FQH) state in absence of magnetic fields. Here we show that
strongly correlated electrons in a t_2g-orbital system on a triangular lattice
self-organize into a spin-chiral magnetic ordering pattern that induces
precisely the required topologically nontrivial and flat bands. This behavior
is very robust and does not rely on fine tuning. In order to go beyond mean
field and to study the impact of longer-range interactions, we map the
low-energy electronic states onto an effective one-band model. Exact
diagonalization is then used to establish signatures of a spontaneous FQH
state.

View original: http://arxiv.org/abs/1109.5955