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Abstract: Magneto-optical measurements in Bi2Sr2CaCu2O8+δ demonstrate enhanced effects of transient disordered vortex states (TDVS) in a prism-shaped sample. The existence of such transient states is indicated by the appearance of a sharp change (‘break’) in the slope of the induction profiles. As the external magnetic field is swept up or down, the break, which signifies the front of the TDVS, moves towards the sample center at a constant velocity determined by the rate of change of the external field. We discuss the results in terms of a competition between injection and annealing processes, the latter being ineffective in the prism due to direct injection of disorder into the bulk through surface barriers distributed along the tilted facets of the prism. [Copyright &y& Elsevier]

Single molecule magnets display fascinating quantum mechanical behavior, and may have important technological applications for information storage and quantum computation. A brief review is given of the physical properties of Mn12-acetate, one of the two prototypical molecular nanomagnets that have been most intensively investigated. Descriptions and discussions are given of the Mn12 magnetic cluster and the fundamental process of quantum tunneling of a nanoscopic spin magnetization; the distinction between thermally-assisted tunneling and pure quantum tunneling, and a study of the crossover between the two regimes; and a review of earlier investigations that suggest that the tunneling in this system is due to locally varying second-order crystal anisotropy which gives rise to a distribution of tunnel splittings. In the second part of the paper, we report results obtained by a new experimental method that confirm our earlier conclusion that the tunnel splittings in Mn12 are distributed rather than single-valued, as had been generally assumed. [Copyright &y& Elsevier]

Abstract: Results demonstrating controlled suppression of magnetization hysteresis in Bi2Sr2CaCu2O8 are presented. We show this suppression at a temperature of 82K and normal magnetic fields up to 20 Oe by applying a dc in-plane field up to 20 Oe. This work shows that in the mentioned region of phase diagram a dc in-plane field overcomes the geometrical barrier. In the presence of an in-plane field, we find vortex chains, formed by Josephson vortices, which extend all the way to the sample edges. We propose that these chains can act as equilibrating channels. This provides insight into the physics underlying the shaking method Avraham et al. (2001), Goldberg et al. (2009) , which is used extensively to equilibrate vortex matter. [ABSTRACT FROM AUTHOR]