Instabilities and disorder-driven first-order transition of the vortex lattice

Transport studies in a Corbino disk suggest that the Bragg glass phase undergoes a first-order transition into a disordered solid. This transition shows sharp reentrant behavior at low fields. In contrast, in the conventional strip configuration, the phase transition is obscured by the injection of the disordered vortices through the sample edges, which results in the commonly observed vortex instabilities and smearing of the peak effect in NbSe2 crystals. These features are found to be absent in the Corbino geometry in which the circulating vortices do not cross the sample edges.     

A comment on a paper of Hamer applying Padé approximants to a 1 + 1 dimensional lattice model of QCD

A method is given for improving the convergence of the sequence of estimates for the energy levels of a 1 + 1 dimensional lattice gauge theory.     

Übergangsmetall—carbin-komplexe LIV. Neue metallocenylcarben- und - carbinkompexe der VI. Nebengruppe – darstellung,vergleich und elektrochemisches verhalten

The lithiated metallocenes ruthenocene (C₅H₅)₂Ru and 1,1′ -dimethylferrocene (C₅H₄CH₃)₂Fe react with the metal hexacarbonyls of Group VIB to yield acylato complexes, from which, by subsequent alkylation with [Et₃O][BF₄], the corresponding pentacarbonylethoxyrunthenocenylcarbene (I—III) as well as pentacarbonylethoxydimethylferrocenylcarbene complexes (IV—VI) of chromium, molybdenum and tungsten are obtained. The reaction of the new tungsten complexes III + VI with boron and aluminium halides (MX₃; X = Cl, Br) at low temperatures yields trans-halogenotetracarbonylruthenocenylcarbyne (VII, VIII) and trans-bromotetracarbonyldimethylferrocenylcarbyne complexes (IX). The reaction conditions, the results of spectroscopic and electrochemical measurements, compared to previously discussed ferrocenylcarbene- and -carbyne complexes and the X-ray structure of III are reported.