Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 85: Superconductivity: Higgs Modes in Condensed Matter and Quantum Gases (jointly with DY, MA, O)

TT 85.1: Hauptvortrag

Donnerstag, 19. März 2015, 09:30–10:00, H 2053

A Brisk Walk through Phase Transitions in Time: Oscillating Order and the Dynamics of Topological Defects — •Dragan Mihailovic — Jozef Stefan Institute, Ljubljana, Slovenia

New techniques in time-resolved optical spectroscopy allow us to investigate phase transitions under controlled, yet highly non-ergodic conditions. The measurement of the temporal evolution of not only single particle and collective excitations, but also topological excitations through the transition lead to a new insight into the emergence of functional properties under non-equilibrium conditions. Experiments on well-known rare earth and transition metal chalcogenides which I will discuss reveal some unexpected phenomena. For example, femtosecond coherent oscillations of the order parameter and the subsequent coherent creation and annihilation of topological defects leads to a transient domain structure which decays through the emission of dispersive Higgs-like amplitude waves [1,2]. Remarkably, if the conditions are right (defined by the material), the topological defects may form an ordered metastable state, which is topologically protected, opening a route to the creation of hidden states [3]. Such switching between states with different charge order occurs at unprecedented speeds and is of potential interest for ultrafast non-volatile memory technology, with either optical or electrical control.

[1] R. Yusupov et al., Nature Phys. 6, 681 (2010)

[2] D. Mihailovic et al., J. Phys.: Condens. Matter 25, 404206 (2013)

[3] L. Stojchevska et al., Science 344, 177 (2014)