Femtosecond Photodoping Phenomena in Cuprate high-Tc Superconductors
Event details
| Date | 22.03.2012 |
| Hour | 15:30 › 17:00 |
| Speaker |
Jure Demsar Physics Department, University of Konstanz, D-78457 Konstanz, Germany |
| Location | |
| Category | Conferences - Seminars |
Ultrafast processes in superconductors (in particular in high-Tc cuprates) excited with femtosecond optical pulses have been intensively studied for over two decades. While most of the studies have been performed in a simple single-color optical pump-probe configuration, novel broad band spectrally resolved studies are being used nowadays to obtain detailed information about the interplay between various degrees of freedom (electrons, spin, lattice) and their interaction strengths.
In this seminar I will first present the recent systematic study of superconducting gap dynamics in a standard BCS superconductor NbN [1]. Based on this benchmark study I will review the findings obtained on high-Tc cuprates, focusing in particular on results obtained with time-resolved THz techniques which enable direct access to the SC condensate [2,3,4] and high frequency phonon dynamics [4].
Following this I will present the first systematic photodoping studies of La2-xSrxCuO4 (0<x<0.35), aiming at determining the nature of low energy excitations in cuprates and its evolution upon doping the charge-transfer insulating ground state. In particular, by studying the dynamics of the complex dielectric function over 0.5-2.8 eV range as a function of excitation conditions important information about the nature of mid-infrared absorption and charge-transfer excitations can be obtained, challenging the existing theoretical models.
[1] M. Beck, et al., Phys. Rev. Lett. 107, 177007 (2011).
[2] R. D. Averitt et al., Phys. Rev. B 63, 140502(R) (2001); R. A. Kaindl et al., Phys. Rev. B 72, 060510 (2005); J. Demsar et al., Phys. Rev. Lett. 91, 267002 (2003); R. A. Kaindl et al., Science 287, 470 (2000).
[3] M. Beyer, et al., Phys. Rev. B 83, 214515 (2011).
[4] A. Pashkin, et al., Phys. Rev. Lett. 105, 067001 (2010).
In this seminar I will first present the recent systematic study of superconducting gap dynamics in a standard BCS superconductor NbN [1]. Based on this benchmark study I will review the findings obtained on high-Tc cuprates, focusing in particular on results obtained with time-resolved THz techniques which enable direct access to the SC condensate [2,3,4] and high frequency phonon dynamics [4].
Following this I will present the first systematic photodoping studies of La2-xSrxCuO4 (0<x<0.35), aiming at determining the nature of low energy excitations in cuprates and its evolution upon doping the charge-transfer insulating ground state. In particular, by studying the dynamics of the complex dielectric function over 0.5-2.8 eV range as a function of excitation conditions important information about the nature of mid-infrared absorption and charge-transfer excitations can be obtained, challenging the existing theoretical models.
[1] M. Beck, et al., Phys. Rev. Lett. 107, 177007 (2011).
[2] R. D. Averitt et al., Phys. Rev. B 63, 140502(R) (2001); R. A. Kaindl et al., Phys. Rev. B 72, 060510 (2005); J. Demsar et al., Phys. Rev. Lett. 91, 267002 (2003); R. A. Kaindl et al., Science 287, 470 (2000).
[3] M. Beyer, et al., Phys. Rev. B 83, 214515 (2011).
[4] A. Pashkin, et al., Phys. Rev. Lett. 105, 067001 (2010).
Practical information
- Informed public
- Free
- This event is internal
Organizer
- EPFL/FSB/ICMP/LUMES, Laboratory for Ultrafast Microscopy and Electron Scattering
Contact
- Fabrizio Carbone ([email protected])