Regensburg 2013 – scientific programme

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SYSD: Symposium SKM Dissertation-Prize 2013

SYSD 1: SKM Dissertation-Prize 2013

SYSD 1.2: Invited Talk

Monday, March 11, 2013, 11:55–12:20, H2

Ultrafast Dynamics of Charge Density Wave Order in DyTe₃ — •Laurenz Rettig — Universität Duisburg-Essen, Lotharstr. 1, 47048 Duisburg

Understanding the collective behavior connected to symmetry-breaking phase transitions and their microscopic effects is a fundamental goal in condensed matter physics. Here, especially the influence of broken symmetry and collective motions on the electronic structure is of great interest. While the underlying competing interactions are often difficult to disentangle using conventional equilibrium methods such as angle-resolved photoemission spectroscopy (ARPES), ultrafast time-resolved spectroscopies can help separating various contributions in the time domain. Here, we use femtosecond (fs) time-resolved ARPES (trARPES) to study the transient electronic band structure of the prototypical charge density wave (CDW) compound DyTe₃ after intense optical excitation. The time-resolved Fermi surface (FS) mapping using a novel position-sensitive time-of-flight spectrometer reveals the collapse of the CDW energy gap within 200 fs.

Furthermore, the momentum-dependent analysis of the transient occupied and unoccupied band dispersion allows for a direct measure of the time-dependent order parameter and reveals an asymmetry in the closing of the CDW energy gap, which depends on the position on the FS. This asymmetry demonstrates a transient modification of the CDW nesting condition on a fs time scale and allows insight into the microscopic orbital overlap during the transition to a state of higher symmetry. This study was supported by the DFG.