FisMat2017 - Submission - View

Abstract's title: Jahn-Teller and excitons contributions in the 1T-TiSe2 charge density wave system
Submitting author: Ettore Carpene
Affiliation: IFN-CNR
Affiliation Address: IFN-CNR c/o Dipartimento di Fisica Politecnico di Milano piazza Leonardo da Vinci 32 20133 Milano - Italy
Country: Italy
Oral presentation/Poster (Author's request): Oral presentation
Other authors and affiliations: H. Hedayat (1), D. Bugini (1), C. Dallera (1), S. Dal Conte (1), G. Cerullo (1), C. Sayers (2) E. Da Como (2), S. Karbassi (3), S. Friedmann (3), J. van Wezel (4) (1) Dipartimento di Fisica, Politecnico di Milano, 20133 Milano, Italy (2) Department of Physics and Centre for Photonics and Photonic Materials, University of Bath, BA2 7AY Bath, UK (3) HH Wills Physics Laboratory, University of Bristol, BS8 1TL Bristol UK (4) Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, 1090 GL Amsterdam, The Netherlands

The driving force leading to the charge-density-wave (CDW) phase transition in 1T-TiSe2 is still highly debated. Among the proposed mechanisms, the excitonic insulators model, i.e. the Coulomb interaction between holes of the valence band and electrons in the conduction band, has gained major attention thanks to recent time-resolved experiments [1,2]. However, lattice distortion and electron-lattice interaction also play an important role, as suggested by theoretical calculations [3,4]. We employed femtosecond time- and angle-resolved photoemission spectroscopy to investigate the photo-induced melting of CDW in 1T-TiSe2 single crystals. Our measurements reveal that spectral weight and energy position of the valence band undergo different dynamics after photo-excitation with ultrashort visible laser pulses. This discrepancy is analyzed in the contest of the excitonic model and the band-type Jahn-Teller mechanism.



[1] C. Monney et al., Phys. Rev. B 94, 165165 (2016).

[2] S. Hellman et al., Nat. Commun. 3, 1069 (2012).

[3] J. Van Wezel et al., Phys. Rev. B 81, 165109 (2010).

[4] K. Rossnagel et al., Phys. Rev. B 65, 235101 (2002).