Optical properties of a vibrationally modulated solid state Mott insulator.
Optical pulses at THz and mid-infrared frequencies tuned to specific vibrational resonances modulate the lattice along chosen normal mode coordinates. In this way, solids can be switched between competing electronic phases and new states are created. Here, we use vibrational modulation to make electronic interactions (Hubbard-U) in Mott-insulator time dependent. Mid-infrared optical pulses excite localized molecular vibrations in ET-F2TCNQ, a prototypical one-dimensional Mott-insulator. A broadband ultrafast probe interrogates the resulting optical spectrum between THz and visible frequencies. A red-shifted charge-transfer resonance is observed, consistent with a time-averaged reduction of the electronic correlation strength U. Secondly, a sideband manifold inside of the Mott-gap appears, resulting from a periodically modulated U. The response is compared to computations based on a quantum-modulated dynamic Hubbard model. Heuristic fitting suggests asymmetric holon-doublon coupling to the molecules and that electron double-occupancies strongly squeeze the vibrational mode.
1] Max-Planck-Institute for the Structure and Dynamics of Matter, Hamburg, Germany [2].
S
S
Kaiser
1] Centre for Quantum Technologies, National University of Singapore, Singapore [2] Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford, UK [3].
S R
SR
Clark
1] Max-Planck-Institute for the Structure and Dynamics of Matter, Hamburg, Germany [2].
D
D
Nicoletti
1] Max-Planck-Institute for the Structure and Dynamics of Matter, Hamburg, Germany [2] Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford, UK.
G
G
Cotugno
Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford, UK.
R I
RI
Tobey
Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford, UK.
N
N
Dean
CNR-IOM and Department of Physics, University of Rome "La Sapienza", Rome, Italy.
S
S
Lupi
Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan.
H
H
Okamoto
National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
T
T
Hasegawa
1] Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford, UK [2] Centre for Quantum Technologies, National University of Singapore, Singapore.
D
D
Jaksch
1] Max-Planck-Institute for the Structure and Dynamics of Matter, Hamburg, Germany [2] Department of Physics, Oxford University, Clarendon Laboratory, Parks Road, Oxford, UK.
A
A
Cavalleri