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TT: Fachverband Tiefe Temperaturen

TT 71: 2D Materials beyond Graphene -Dynamics and Excitation
(Joint session of DS, DY, HL, MA, O and TT organized by O)

TT 71.10: Vortrag

Donnerstag, 10. März 2016, 13:00–13:15, S054

Ultrafast carrier multiplication in 1T-TiSe₂ — •Stephan Michael¹, Steffen Eich¹, Henry C. Kapteyn², Margaret M. Murnane², Michael Bauer³, Kai Rossnagel³, Hans Christian Schneider¹, Martin Aeschlimann¹, and Stefan Mathias⁴ — ¹University of Kaiserslautern — ²JILA, University of Colorado and NIST — ³University of Kiel — ⁴University of Göttingen

1T-TiSe₂ is a transition metal dichalcogenide, which has a charge density wave (CDW) state below a temperature of around 200 K, which may be due to an excitonic insulator mechanism and/or an Jahn-Teller effect. We studied optically excited carrier dynamics on ultrashort timescales in the CDW phase using time-resolved ARPES measurements and an effective two-band model including carrier-carrier Coulomb scattering. In the framework of this model we analyze the ultrafast response of this material to optical excitation, which is seen in the experiment. We show that carrier multiplication in the form of impact ionization is the most satisfactory explanation for the ultrafast redistribution of spectral weight observed in the ARPES measurements.