Origin of flat-band superfluidity on the Mielke checkerboard lattice

Geometric Origin of Superfluidity in the Lieb-Lattice Flat Band.

The ground state and transport properties of the Lieb lattice flat band in the presence of an attractive Hubbard interaction are considered. It is shown that the superfluid weight can be large even for an isolated and strictly flat band. Moreover the superfluid weight is proportional to the interaction strength and to the quantum metric, a band structure quantity derived solely from the flat-ba...

Flat-band excitonic states in Kagome lattice on semiconductor surfaces

Recent surface techniques to fabricate and arrange quantum wires on the semiconductor surface have enabled to synthesize the artificial two-dimensional lattice systems such as square and triangle lattices. For example, C. Albrecht et al. produced a square lattice by arranging InAs wires on GaInAs (001) surface and showed that a butterfly energy spectra is seen in the case of applying the magnet...

Discrete flat-band solitons in the kagome lattice

Flat - Bands on Partial Line Graphs — Systematic Method for Generating Flat - Band Lattice Structures —

We introduce a systematic method for constructing a class of lattice structures that we call “partial line graph”s. In tight-binding models on partial line graphs, energy bands with flat energy dispersions emerge. This method can be applied to twoand three-dimensional systems. We show examples of partial line graphs of square and cubic lattices. The method is useful in providing a guideline for...

Superfluidity in topologically nontrivial flat bands.

Topological invariants built from the periodic Bloch functions characterize new phases of matter, such as topological insulators and topological superconductors. The most important topological invariant is the Chern number that explains the quantized conductance of the quantum Hall effect. Here we provide a general result for the superfluid weight Ds of a multiband superconductor that is applic...