Doping dependence of the vortex glass and sublimation transitions in the high-TcT_{c} superconductor La2−x_{2-x}Srx_{x}CuO4_{4} as determined from macroscopic measurements

Magnetization and ac-susceptibility measurements are used to characterize the mixed phase of the high-temperature cuprate superconductor La$_{2-x}$Sr$_{x}$CuO$_{4}$ over a large range of doping (0.075 $\leq x\leq$ 0.20). The first order vortex lattice phase transition line $H_{FOT}(T)$, the upper critical field $H_{c2}(T)$ and the second peak $H_{sp}(T)$ have been investigated up to high magnetic fields (8 Tesla applied perpendicular to the $CuO_2$ planes). Our results reveal a strong doping dependence of the magnetic phase diagram, which can mainly be explained by the increasing anisotropy with underdoping. Within our interpretation, the first order vortex lattice phase transition is due to the sublimation (rather than melting) of the vortex lattice into a gas of pancake vortices, whereas the second peak is related to the transition to a more disordered vortex glass state.Comment: 7 pages, 5 figure

The Pennsylvania Comparative Negligence Act - An Alien Intruder in the House of Common Law

Using the Pennyslvania [sic] legislature\u27s recent enactment of a comparative negligence statute as a vehicle, the author asserts that the courts can and should reevaluate common law concepts as they apply to cases which, although pending at the time of a legislative change in the common law, are not subject to the basically prospective statutory provisions

A small angle neutron scattering study of the vortex matter in La{2-x}Sr{x}CuO{4} (x=0.17)

The magnetic phase diagram of slightly overdoped La{2-x}Sr{x}CuO{4} (x=0.17) is characterised by a field-induced hexagonal to square transition of the vortex lattice at low fields (~0.4 Tesla) [R. Gilardi et al., Phys. Rev. Lett. 88, 217003 (2002)]. Here we report on a small angle neutron scattering study of the vortex lattice at higher fields, that reveals no further change of the coordination of the square vortex lattice up to 10.5 Tesla applied perpendicular to the CuO2 planes. Moreover, it is found that the diffraction signal disappears at temperatures well below Tc, due to the melting of the vortex lattice.Comment: 3 pages, 2 figures. Presented at the New3SC-4 meeting, San Diego, Jan. 16-21 2003; to be published in Int. J. Mod. Phys.