Non-Abelian Quantum Hall Effect in Topological Flat Bands

Inspired by recent theoretical discovery of robust fractional topological phases without a magnetic field, we search for the non-Abelian quantum Hall effect (NA-QHE) in lattice models with topological flat bands (TFBs). Through extensive numerical studies on the Haldane model with three-body hard-core bosons loaded into a TFB, we find convincing numerical evidence of a stable $\nu=1$ bosonic NA-QHE, with the characteristic three-fold quasi-degeneracy of ground states on a torus, a quantized Chern number, and a robust spectrum gap. Moreover, the spectrum for two-quasihole states also shows a finite energy gap, with the number of states in the lower energy sector satisfying the same counting rule as the Moore-Read Pfaffian state.Comment: 5 pages, 7 figure

Fractional Quantum Hall Effect of Hard-Core Bosons in Topological Flat Bands

Recent proposals of topological flat band (TFB) models have provided a new route to realize the fractional quantum Hall effect (FQHE) without Landau levels. We study hard-core bosons with short-range interactions in two representative TFB models, one of which is the well known Haldane model (but with different parameters). We demonstrate that FQHE states emerge with signatures of even number of quasi-degenerate ground states on a torus and a robust spectrum gap separating these states from higher energy spectrum. We also establish quantum phase diagrams for the filling factor 1/2 and illustrate quantum phase transitions to other competing symmetry-breaking phases.Comment: 4 pages, 6 figure

Diaqua­bis(benzyl­oxyacetato)copper(II)

In the title mononuclear complex, [Cu(C9H9O3)2(H2O)2], the CuII ion, located on an inversion center, is hexa­coordinated by four O atoms from two benzyl­oxyacetate ligands [Cu—O = 1.9420 (14) and 2.2922 (14) Å] and two water mol­ecules [Cu—O = 2.0157 (15) Å] in a distorted octa­hedral geometry. In the crystal structure, inter­molecular O—H⋯O hydrogen bonds link the mol­ecules into layers parallel to the bc plane

Bis­(1H-benzimidazole-κN 3)bis(4-methyl­benzoato-κ 2 O,O′)cobalt(II)

In the title mononuclear complex, [Co(C8H7O2)2(C7H6N2)2], the CoII atom is coordinated by four carboxylate O atoms from two 4-methyl­benzoate ligands and two N atoms from two benzimidazole ligands in an octa­hedral coordination geometry. The molecules are assembled via inter­molecular N—H⋯O hydrogen-bonding inter­actions into a three-dimensional network

Poly[[μ2-aqua-aqua­(μ3-3,5-dinitro­salicylato)barium(II)] monohydrate]

In the title coordination polymer, {[Ba(C7H2N2O7)(H2O)2]·H2O}n, the BaII atom is ten-coordinated by seven O atoms from four 3,5-dinitro­salicylatate ligands, two μ2-bridging aqua ligands and one water mol­ecule. The coordination mode is best described as a bicapped square-anti­prismatic geometry. The 3,5-dinitrosalicylatate ligands bridge three Ba atoms. Centrosymmetrically related dinuclear barium units, with a Ba⋯Ba separation of 4.767 (5) Å, form infinite chains, which are further self-assembled into a supra­molecular network through inter­molecular O—H⋯O hydrogen-bonding inter­actions between O atoms of 3,5-dinitro­salicylatate ligands and water mol­ecules

Poly[aqua­(μ2-oxalato)(4-oxidopyri­din­ium)erbium(II)]

The title complex, [Er(C5H5NO)(C2O4)(H2O)]n, is a new erbium polymer based on oxalate and 4-oxidopyridinium ligands. The ErII center is coordinated by six O atoms from three oxalate ligands, one O atom from a 4-oxidopyridinium ligand and one water mol­ecule, and displays a distorted square-anti­prismatic coordination geometry. The oxalate ligands are both chelating and bridging, and link ErII ions, forming Er–oxalate layers in which the attached water and 4-oxidopyridinium units point alternately up and down. A mirror plane passes through the Er atom, one C, the oxide O and two oxalate O atoms. The layers are assembled into a three-dimensional supra­molecular network via inter­molecular hydrogen bonding and π–π stacking inter­actions [centroid–centroid distances of 3.587 (2) Å between parallel pyridinium rings]. Both the water mol­ecule and the 4-oxidopyridinium ligand are disordered over two sites in a 1:1 ratio