Correlated vortex pinning in slightly orthorhombic twinned Ba(Fe1−xCox)2As2 single crystals: Possible shift of the vortex-glass/liquid transition

The interest in twin-boundary (TB) planes as a source of vortex pinning has been recently renewed with the discovery of the new iron-arsenide pnictide superconductors. In the family of compounds Ba(Fe1−xCox )2As2 a structural transition from a tetragonal to orthorhombic lattice takes place for compounds with xxcr) there is no twinning and we find good agreement with the expected scaling function under uncorrelated disorder, with small anisotropy values similar to those reported in the literature. We show that in the orthorhombic samples (xFil: Marziali Bermudez, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Pasquini, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Bud´ko, S.L.. University of Iowa; Estados UnidosFil: Canfield, P.C.. University of Iowa; Estados Unido

Correlated vortex pinning in slightly orthorhombic twinned Ba(Fe1-xCox)(2)As-2 single crystals: Possible shift of the vortex-glass/liquid transition

The interest in twin-boundary (TB) planes as a source of vortex pinning has been recently renewed with the discovery of the new iron-arsenide pnictide superconductors. In the family of compounds Ba(Fe1−xCox)2As2 a structural transition from a tetragonal to orthorhombic lattice takes place for compounds with xxcr) there is no twinning and we find good agreement with the expected scaling function under uncorrelated disorder, with small anisotropy values similar to those reported in the literature. We show that in the orthorhombic samples (xThis article is published as Bermúdez, M. Marziali, G. Pasquini, Sergey L. Bud'ko, and Paul C. Canfield. "Correlated vortex pinning in slightly orthorhombic twinned Ba (Fe 1− x Co x) 2 As 2 single crystals: Possible shift of the vortex-glass/liquid transition." Physical Review B 87, no. 5 (2013): 054515. DOI: 10.1103/PhysRevB.87.054515. Posted with permission.</p

Metastability and hysteretic vortex pinning near the order-disorder transition in NbSe2: Interplay between plastic and elastic energy barriers

We studied thermal and dynamic history effects in the vortex lattice (VL) near the order-disorder transition in clean NbSe2 single crystals. Comparing the evolution of the effective vortex pinning and the bulk VL structure, we observed metastable superheated and supercooled VL configurations that coexist with a hysteretic effective pinning response due to thermal cycling of the system. A novel scenario, governed by the interplay between (lower) elastic and (higher) plastic energy barriers, is proposed as an explanation for our observations: Plastic barriers, which prevent the annihilation or creation of topological defects, require dynamic assistance to be overcome and to achieve a stable VL at each temperature. Conversely, thermal hysteresis in the pining response is ascribed to low energy barriers, which inhibit rearrangement within a single VL correlation volume and are easily overcome as the relative strength of competing interactions changes with temperature.Fil: Marziali Bermudez, Mariano. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Louden, E. R.. University of Notre Dame; Estados UnidosFil: Eskildsen, M. R.. University of Notre Dame; Estados UnidosFil: Dewhurst, C. D.. Institut Laue Langevin; FranciaFil: Bekeris, Victoria Isabel. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Pasquini, Gabriela. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin