Fidelity and superconductivity in two-dimensional t-J models

We compute the ground-state fidelity and various correlations to gauge the competition between different orders in two-dimensional t-J-type models. Using exact numerical diagonalization techniques, these quantities are examined for (i) the plain t-J and t-t'-J models, (ii) for the t-J model perturbed by infinite-range d-wave or extended-s-wave superconductivity inducing terms, and (iii) the t-J model, plain and with a d-wave perturbation, in the presence of non-magnetic quenched disorder. Various properties at low hole doping are contrasted with those at low electron filling. In the clean case, our results are consistent with previous work that concluded that the plain t-J model supports d-wave superconductivity. As a consequence of the strong correlations present in the low hole doping regime, we find that the magnitude of the d-wave condensate occupation is small even in the presence of large d-wave superconductivity inducing terms. In the dirty case, we show the robustness of the ground state in the strongly correlated regime against disorder.Comment: 11 pages, 12 figures, as publishe

Effects of Strong Correlations and Disorder in d-Wave Superconductors

We use exact diagonalization techniques to study the interplay between strong correlations, superconductivity, and disorder in a model system. We study an extension of the t-J model by adding an infinite-range d-wave superconductivity inducing term and disorder. Our work shows that in the clean case the magnitude of the order parameter is surprisingly small for low-hole filling, thus implying that mean-field theories might be least accurate in that important regime. We demonstrate that substantial disorder is required to destroy a d-wave superconducting state for low-hole doping. We provide the first bias free numerical results for the local density of states of a strongly correlated d-wave superconducting model, relevant for STM measurements at various fillings and disorders.Comment: 4 pages, 4 figures, as publishe

Synthesis of a hexasaccharide partial sequence of hyaluronan for click chemistry and more

In the present work, the synthesis of a hexasaccharide partial sequence of hyaluronan equipped with a terminal azido moiety is reported. This hexasaccharide can be used for the attachment on surfaces by means of click chemistry and after suitable deprotection for biophysical studies

Hünlich Base: (Re)Discovery, Synthesis, and Structure Elucidation after a Century

After almost 100 years, the structure of the product of the reaction between 2,4-diaminotoluene and formaldehyde was elucidated: derivative <b>3</b>, which we call the Hünlich base, was synthesized on a multigram scale and its enantiomers were easily separated in preparative amounts. Furthermore, transformation of the NH₂ groups to the corresponding bis-iodides and bis-azides is presented. The latter was also used for desymmetrization by click chemistry

Hünlich Base: (Re)Discovery, Synthesis, and Structure Elucidation after a Century

After almost 100 years, the structure of the product of the reaction between 2,4-diaminotoluene and formaldehyde was elucidated: derivative <b>3</b>, which we call the Hünlich base, was synthesized on a multigram scale and its enantiomers were easily separated in preparative amounts. Furthermore, transformation of the NH₂ groups to the corresponding bis-iodides and bis-azides is presented. The latter was also used for desymmetrization by click chemistry