Thermal hysteresis and dynamic history effects in vortex matter

报告题目:Thermal hysteresis and dynamic history effects in vortex matter

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



报告摘要:In a variety of complex systems, among witch vortex matter is a prototype, glassybehavior and metastable configurations give rise to striking history effects closelyconnected with a rich dynamics where plasticity plays a key role. Superconductingmaterials with randomly distributed weak pinning centers are an ideal playground forresearch. In this talk I will present a whole picture built during the last decade by ourgroup to explain thermal and dynamic history effects observed in vortex matter. Thekey results were obtained by performing joint AC susceptibility measurements andsmall angle neutron diffraction experiments in clean NbSe2 single crystals. I willreview one of our main result that shows direct evidence of the existence of a regionin the phase diagram, where the application of shaking AC fields gives rise to bulkvortex lattice (VL) configurations with intermediate dislocation densities, correlatedwith intermediate effective pinning. I will also show that thermal and dynamic historyeffects are revealed as qualitatively different, and discuss how the thermal hysteresiscan be theoretically explained in term of the strong pinning theory.

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.