Polaronic Conductivity in the Photoinduced Phase of $1T\mathrm{\text{\ensuremath{-}}}{\mathrm{TaS}}_{2}$

Polaronic Conductivity in the Photoinduced Phase of $1 T − {TaS}_{2}$

N. Dean, J. C. Petersen, D. Fausti, R. I. Tobey, S. Kaiser, L. V. Gasparov, H. Berger, and A. Cavalleri

Phys. Rev. Lett. 106, 016401 – Published 4 January 2011

Abstract

The transient optical conductivity of photoexcited $1 T − {TaS}_{2}$ is determined over a three-order-of-magnitude frequency range. Prompt collapse and recovery of the Mott gap is observed. However, we find important differences between this transient metallic state and that seen across the thermally driven insulator-metal transition. Suppressed low-frequency conductivity, Fano phonon line shapes, and a midinfrared absorption band point to polaronic transport. This is explained by noting that the photoinduced metallic state of $1 T − {TaS}_{2}$ is one in which the Mott gap is melted but the lattice retains its low-temperature symmetry, a regime only accessible by photodoping.

Received 1 September 2010

DOI:https://doi.org/10.1103/PhysRevLett.106.016401

Authors & Affiliations

N. Dean^1,*, J. C. Petersen^1,2, D. Fausti^1,2, R. I. Tobey^1,3, S. Kaiser², L. V. Gasparov⁴, H. Berger⁵, and A. Cavalleri^1,2,†

¹Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom
²Max Planck Department for Structural Dynamics, University of Hamburg, Centre for Free Electron Laser Science, Notkestraße 85, 22607 Hamburg, Germany
³Condensed Matter Physics and Material Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA
⁴Department of Chemistry and Physics, University of North Florida, 4567 St. Johns Bluff Road, South Jacksonville, Florida 32224, USA
⁵Institue of Physics of Complex Matter, École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

^*Corresponding author. n.dean1@physics.ox.ac.uk
^†Corresponding author. andrea.cavalleri@mpsd.cfel.de

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Vol. 106, Iss. 1 — 7 January 2011

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Physical Review Letters

Polaronic Conductivity in the Photoinduced Phase of 1T−TaS2

N. Dean, J. C. Petersen, D. Fausti, R. I. Tobey, S. Kaiser, L. V. Gasparov, H. Berger, and A. Cavalleri

Phys. Rev. Lett. 106, 016401 – Published 4 January 2011

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Polaronic Conductivity in the Photoinduced Phase of $1 T − {TaS}_{2}$