Regensburg 2016 – scientific programme
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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: Talk
Thursday, March 10, 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.