Complex Phase Diagram of Doped XXZ Ladder: Localization and Pairing

How the ground state nature can be dramatically changed by the distinct underlying spin correlation is a central issue of doped Mott insulators. The two-leg XXZ ladder provides a prototypical spin background, which can be tuned from a long-range N\'{e}el order to a short-range ``spin liquid'' via the superexchange anisotropy, giving rise to a complex phase diagram at finite doping. By density matrix renormalization group method, we show that although the charge is always self-localized in the N\'{e}el ordered phase, a second insulating phase emerges, in which the doped holes become paired but remain localized while the transverse spin-spin correlation reduces to short-ranged one to make the N\'{e}el order classical. Only when the N\'{e}el order totally disappears by further reducing anisotropy, does the pairing become truly coherent as characterized by a Luther-Emery state. In sharp contrast, the pairing is totally absent in the in-plane ferromagnetic XXZ regime, where a direct transition from the charge self-localization in the N\'{e}el ordered phase to a Fermi-gas-like state in the spin liquid phase is found. A consistent physical picture is briefly discussed.Comment: 9 pages, 9 figure

Tetra­aqua­tetra­kis{μ3-3,3′-[(E,E)-ethane-1,2-diylbis(nitrilo­methyl­idyne)]benzene-1,2-diolato}octa­zinc(II) N,N-dimethyl­formamide hexa­solvate

The asymmetric unit of the title compound [Zn8(C16H12N2O4)4(H2O)4]·6C3H7NO, consists of eight ZnII cations, four tetra­valent anionic ligands, L 4− (L 4− = 3,3′-(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-yl­idene))bis­(methan-1-yl-1-yl­idene)dibenzene-1,2-bis­(olate), four coordinated water mol­ecules and six N,N-dimethyl­formamide solvate mol­ecules. The coordination complex comprises an octa­nuclear ZnII unit with its ZnII centers coordinated in two discrete distorted square-pyramidal geometries. Four ZnII atoms each coordinate to two nitro­gen atoms and two phenolate oxygen atoms from an individual L 4− ligand and one coordinated water mol­ecule. The other four ZnII atoms each bind to five phenolate oxygen atoms from three different L 4− ligands. In the crystal structure, the ZnII complex unit, coordinated water mol­ecules and dimethyl­formamide solvate mol­ecules are linked via O—H⋯O and C—H⋯O hydrogen bonds. Mol­ecules are connected by additional inter­molecular O—H⋯O and C—H⋯O hydrogen bonds, forming an extensive three dimensional framework

Pair density wave characterized by a hidden string order parameter

A composite pairing structure of superconducting state is revealed by density matrix renormalization group study in a two-leg $t$-$J$ model. The pairing order parameter is composed of a pairing amplitude and a phase factor, in which the latter explicitly depends on the spin background with an analytic form identified in the anisotropic limit as the interchain hopping integral $t_{\perp}\rightarrow 0$. Such a string-like phase factor is responsible for a pair density wave (PDW) induced by spin polarization with a wavevector $Q_{\mathrm {PDW}}=2\pi m$ ($m$ the magnetization). By contrast, the pairing amplitude remains smooth, unchanged by the PDW. In particular, a local spin polarization can give rise to a sign change of the order parameter across the local defect. Unlike in an Fulde-Ferrell-Larkin-Ovchinnikov state, the nonlocal phase factor here plays a role as the new order parameter characterizing the PDW, whose origin can be traced back to the essential sign structure of the doped Mott insulator.Comment: 10 pages, 8 figure

catena-Poly[(chloridozinc)-μ-5-(1-methyl-1H-benzimidazol-2-yl-κN 3)-1,2,3-triazol-1-ido-κ2 N 1:N 3]

In the title complex, [Zn(C10H8N5)Cl]n, the ZnII ion is four-coordinated by one Cl atom and three N atoms from two in situ-generated deprotonated 5-(1-methyl-1H-benzimidazol-2-yl-κN 3)-1,2,3-triazol-1-ide ligands in a slightly distorted tetra­hedral geometry. The ZnII ions are bridged by the ligands, forming a helical chain along [001]. C—H⋯N and C—H⋯Cl hydrogen bonds and π–π inter­actions between the imidazole rings [centroid–centroid distance = 3.4244 (10) Å] assemble the chains into a three-dimensional supra­molecular network

Halogen Bonds in Two Silver(I) Mixed-ligand Supramolecular Frameworks: Synthesis, Structure and Photoluminescence

Two silver(I) tetrachlorophthalates incorporating aminopyrimidyl ligands, namely [Ag 4 (apym) 4 (tcpta) 2 ] n (1) and [Ag 2 (dmapym)(tcpta)] n (2), (apym = 2-aminopyrimidine, dmapym = 2-amino-4,6-dimethylpyrimidine, H 2 tcpta = tetrachlorophthalic acid), were synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Both 1 and 2 form sheets which are assembled into 3D supramolecular frameworks via halogen bonds, hydrogen bonds and π ···π interactions. Even adding two more methyl groups to the pyrimidyl ring does not change the dimensions of 1 and 2, but it influences the arrangement of the N-and O-donors in the solid state which in turn results in different types of halogen bonds. The photoluminescence properties of 1 and 2 were investigated in the solid state at room temperature

Prognostic factors in patients with complete response of the tumour (ypT0) after neoadjuvant chemoradiotherapy and radical resection of rectal cancer

Background There are only a few studies on the prognosis of patients with complete response of the tumour (ypT0) after neoadjuvant chemoradiotherapy (NCRT) and radical resection of rectal cancer. The aim of the study was to identify prognostic factors with regard to oncological outcome in ypT0 patients after NCRT and radical resection. Methods All ypT0 patients with rectal cancer after NCRT and radical resection between January 2010 and June 2019 were included. Cox univariate and multivariate regression analyses were used to determine the prognostic factors of these patients. Results Seventy-six patients with ypT0 rectal cancer were included. In nine patients (11.8%), lymph node metastasis was identified. Age, gender, elevated carcinoembryonic antigen (CEA) and ypN+ were risk factors associated with a worse 5-year disease-free survival (DFS) rate in univariate analysis (P = 0.08, 0.14, 0.007 and 0.003, respectively). In multivariate analysis, ypN+ and elevated CEA before NCRT were independent risk factors for worse 5-year DFS (P = 0.005 and 0.021, respectively). Elevated CEA before NCRT, post-operative chemotherapy and ypN+ were risk factors associated with worse overall survival in univariate analysis (P = 0.14, 0.002 and 0.17, respectively). However, in multivariate analysis, none of these three factors were independent risk factors for worse overall survival (P = 0.20, 0.34 and 0.06, respectively). Conclusion ypN+ and elevated CEA before NCRT were found to be independent risk factors for an unfavourable DFS in ypT0 patients with complete response of the tumour after neoadjuvant chemoradiotherapy for rectal cancer

Benzo[a]fluoren-11-one

The mol­ecule of the title compound, C17H10O, is nearly planar, the largest deviation from the mean plane being 0.06 Å. The crystal structure is governed by π–π inter­actions, with centroid–centroid distances ranging from .559 to 3.730 Å

1-[4-(Dimethylamino)benzylidene]-4-(4-nitro-phenyl)thiosemicarbazide

通讯作者地址: Huang, RB (通讯作者), Xiamen Univ, Dept Chem, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Dept Chem, Xiamen 361005, Peoples R China 2. Xiamen Univ, State Key Lab Phys Chem Solid Surface, Xiamen 361005, Peoples R ChinaIn the title compound, C16H17N5O2S, the configuration is trans about the formal C = N bond. The molecular conformation is stabilized by an intramolecular N - H center dot center dot center dot N hydrogen bond