Dynamics in correlated materials probed by femtosecond XUV photoemission

Date

Aug 27, 2013

Time

9:30 AM - 10:15 AM

Speaker

Michael Bauer

Language

en

Main Topic

Physik

Other Topics

Physik

Host

QSOE13

Description

The combination of femtosecond light sources in the UV spectral regime and the technique of photoelectron spectroscopy provides a unique tool for tracking ultrafast processes in condensed matter systems that couple to electronic degrees of freedom. Angular resolution enables one in this context to monitor the temporal evolution of the valence electronic band structure of a solid at selected - and possibly critical - points in momentum space [1]. The application of XUV photon pulses from high harmonic generation light sources [2] enlarges the accessible momentum regime considerably so that band structure transients within the entire Brillouin zone or even beyond can be recorded [3]. In this contribution, different examples of our work using time-resolved XUV-ARPES will be presented. I will show how this technique enables one to monitor the relaxation dynamics of hot carriers in graphite in a very direct manner by probing the involved electronic states located at the boundary of the Brillouin zone [4]. In a second example I will report on results on the laser-induced melting of charge density wave phases in different compounds out of the class of the transition metal dichalcogenides [5]. This systematic study provides conclusive evidence for the existence of the excitonic insulator phase in 1T -TiSe2 [6]. Finally, some recent time-resolved ARPES data on BaFe2As2 will be presented. We observe a characteristic in-phase oscillation in the electronic structure at the - and the X-point associated with the excitation of the As A1g mode. Potential implications of this experimental finding are made based on a theoretical model which considers the effect of the Fe-As-Fe bond angle onto the electronic structure of BaFe2As2. [1] F. Schmitt et al., Science 321, 1649 (2008). [2] A. Rundquist, et al., Science, 280 1412 (1998). [3] S. Mathias et al., Rev. Sci. Instr. 78, 083105 (2007). [4] A. Stange et al., Eur. Phys. J. Web of Conferences 41, 04022 (2013). [5] T. Rohwer et al., Nature 471, 490 (2011). [6] S. Hellmann et al., Nature Comm. 3, 1069 (2012).

Last modified: Aug 27, 2013, 9:35:57 AM