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SYUE: Symposium Ultrafast Excitation Pathways of Quantum Materials

SYUE 1: Ultrafast Excitation Pathways of Quantum Materials

SYUE 1.3: Invited Talk

Wednesday, March 29, 2023, 10:30–11:00, HSZ 01

Exciting potentials -- Exploring the realms of ultrafast phase transitions — •Laurenz Rettig — Fritz Haber Institute of the Max Planck Society, Berlin, Germany

Phase transitions, ubiquitous in nature, are characterized by breaking of characteristic material symmetries, which can be described by an order parameter. The phase of a material is then determined by the shape and the minima of the free energy surface. While in thermal equilibrium, a system occupies the phase space close to these minima, and phase transitions occur as function of thermodynamic state variables, ultrafast laser excitation allows modifying the energy surfaces on timescales faster than the response time of the system, thereby driving ultrafast phase transitions, and triggering coherent dynamics within the transient energy surfaces. This approach not only provides information about the microscopic couplings behind a phase transition, but also allows for coherent manipulation of material properties.

In my talk, I will discuss recent experiments employing time- and angle-resolved photoemission spectroscopy (trARPES), unearthing rich dynamics of photoinduced phase transitions in prototypical charge-density wave materials, including a transition into a hidden, metastable state.