[institut] SCL seminar: Fractional Chern Insulators, Milica Milovanovic, petak 21. jun u 14:00

[Nenad Vukmirović]

Поштоване колегинице и колеге,

Позивам вас на SCL семинар који ће у петак 21. јуна 2013. године у
14:00 у сали "Звонко Марић" Института за физику да одржи Милица 
Миловановић (SCL, Институт за физику у Београду). Наслов семинара је:

On the geometrical description of fractional Chern insulators

Abstract:

After the prediction and realization of topological insulators [1], 
which may be described as systems with integer quantum Hall effect 
physics without external magnetic field and Landau levels, there is an 
increasing interest in fractional Chern insulators (FCIs), interacting 
systems which without magnetic field would support fractional quantum 
Hall (FQH) physics [2]. In the case of FCIs the role of the fixed Landau 
level is played by a Bloch band with a non-trivial Chern number. The 
structure of the Bloch band depends on the underlying lattice, and may 
be quantified by Berry curvature and Fubini-Study (quantum distance) 
metric that depend on  Bloch momentum in Brillouin zone. The usual FQH 
effect would correspond to a uniform background: constant curvature and 
  metric with a fixed relationship.

In this talk [3] we will study the static structure factor of the FCI 
Laughlin-like state and provide analytical forms for this quantity in 
the long distance limit. In the course of this we will identify 
averaged over Brillouin zone  Fubini Study metric as the relevant metric 
in the long distance limit. We will discuss under which conditions the 
static structure factor will assume the usual behavior of Laughlin-like 
FQH system i.e. the  scenario of Girvin, MacDonald, and Platzman [Phys. 
Rev. B 32, 8458 (1986)], and study the influence of the departure of the 
averaged over Brilloin zone Fubini-Study metric from its FQH value. This 
departure appears in the long distance analysis as an effective change 
of the filling factor. According to our exact diagonalization results on 
the Haldane model and  analytical considerations we  find persistence of 
FCI state even in this region of the parameter space.

[1] M.Z. Hasan and C.L, Kane, "Colloquium: Topological Insulators", Rev. 
Mod. Phys. 82, 3045 (2010)
[2] R. Roy and S.L. Sondhi, "Fractional Quantum Hall Effect without 
Landau levels", Physics 4, 46 (2011); M. Daghofer and M. Haque, "Toward 
Fractional Quantum Hall Physics with Cold Atoms", Physics 6, 49 (2013)
[3] E. Dobardzic, M.V. Milovanovic, and N. Regnault, arXiv:1303.7131

Срдачан поздрав,

-- 
Др Ненад Вукмировић,
Виши научни сарадник,
Лабораторија за примену рачунара у науци,
Институт за физику Београд,
Србија.
URL: http://www.scl.rs/nenad