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.
报告时间:8月16日,周四,晚上6点30
报告地点:红楼东侧小楼204,原发展办
报告摘要:In superconducting materials with randomly distributed weak pinning centers the stable vortex phase at low temperature and low magnetic fields is an ordered dislocation free Bragg Glass. With increasing field and/or temperature, the system undergoes an order-disorder transition to a strongly pinned disordered phase. In this framework, the existence of a transitional region between the ordered and the disordered phases remained a controversial issues for more than a decade. In the previous 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 the ordered and the disordered phases, where the application of shaking AC fields gives rise to bulk VL configurations with intermediate dislocation densities correlated with intermediate effective pinning. Numerical simulations suggested that these “intermediate” configurations are originated from a VL reorganization driven by the oscillatory dynamics. In this talk I will present new experimental results that show clear evidence of this dynamic reordering. Moreover, unambiguous signature of criticality suggests that this reorganization is closely connected with a dynamic phase
transition.
报告人简介:Prof. Gabriela Pasquini obtained her degree in physics and her PhD at Buenos Aires Universtiy, Argentina in 1998, working in AC vortex dynamics in the presence of columnar defects. After a PosDoctoral stay in Tor Vergata University, Rome, she returned back to Argentina 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 the Low Temperature Lab, where she leads the research in vortex physics from 2007. She recently starts developing two new research lines, one of then devoted 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 physics during the last years, to further present recent results that explain some of the experimental features in term of the strong pinning theory. In the second talk, she will present very recent results evidencing a connection between vortex matter reorganization and a critical dynamic phase transition.