AC dynamic reorganization and critical phase transition in vortex matter

报告题目:AC dynamic reorganization and critical phase transition in vortex matter

报告人:Gabriela Pasquini教授,Universidad de Buenos Aires, FCEyN, Departamento de Física, Argentina.



报告摘要:In superconducting materials with randomly distributed weak pinning centers thestable vortex phase at low temperature and low magnetic fields is an ordereddislocation free Bragg Glass. With increasing field and/or temperature, the systemundergoes an order-disorder transition to a strongly pinned disordered phase. In thisframework, the existence of a transitional region between the ordered and thedisordered phases remained a controversial issues for more than a decade. In theprevious talk I have review the main results obtained in the last years by our group,supporting the existence of a narrow in-between transitional region between theordered and the disordered phases, where the application of shaking AC fields givesrise to bulk VL configurations with intermediate dislocation densities correlated withintermediate effective pinning. Numerical simulations suggested that these“intermediate” configurations are originated from a VL reorganization driven by theoscillatory dynamics. In this talk I will present new experimental results that showclear evidence of this dynamic reordering. Moreover, unambiguous signature ofcriticality suggests that this reorganization is closely connected with a dynamic phase

报告人简介:Prof. Gabriela Pasquini obtained her degree in physics and her PhD at BuenosAires Universtiy, Argentina in 1998, working in AC vortex dynamics in thepresence of columnar defects.After a PosDoctoral stay in Tor Vergata University, Rome, she returned back toArgentina in 2001.At the present time GP is an Associated Professor at Buenos Aires University,and a member of CONICET (National research commission). She works in theLow Temperature Lab, where she leads the research in vortex physics from2007. She recently starts developing two new research lines, one of thendevoted to study the connection between nematic and superconducting phases
in Fe-based superconductors.Today she will review the main results obtained by her group in vortex physicsduring the last years, to further present recent results that explain some of theexperimental features in term of the strong pinning theory.In the second talk, she will present very recent results evidencing a connectionbetween vortex matter reorganization and a critical dynamic phase transition.