Ultrafast nematic-orbital excitation in FeSe

Abstract

The electronic nematic phase is an unconventional state of matter that spontaneously breaks the rotational symmetry of electrons. In iron-pnictides/chalcogenides and cuprates, the nematic ordering and fluctuations have been suggested to have as-yet-unconfirmed roles in superconductivity. However, most studies have been conducted in thermal equilibrium, where the dynamical property and excitation can be masked by the coupling with the lattice. Here we use femtosecond optical pulse to perturb the electronic nematic order in FeSe. Through time-, energy-, momentum- and orbital-resolved photo-emission spectroscopy, we detect the ultrafast dynamics of electronic nematicity. In the strong-excitation regime, through the observation of Fermi surface anisotropy, we find a quick disappearance of the nematicity followed by a heavily-damped oscillation. This short-life nematicity oscillation is seemingly related to the imbalance of Fe 3dxz and dyz orbitals. These phenomena show critical behavior as a function of pump fluence. Our real-time observations reveal the nature of the electronic nematic excitation instantly decoupled from the underlying lattice.

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Cited by in corpus (10)

• Nonthermal pathways to ultrafast control in quantum materials
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Exotic Superconducting States in FeSe-based Materials
• Orientational order parameters for arbitrary quantum systems
• Pressure-induced reconstitution of Fermi surfaces and spin fluctuations in S-substituted FeSe
• Pure nematic state in iron-based superconductor
• Field theory for the dynamics of the open $O(N)$ model
• Cu doping effects on the electronic structure of Fe1-xCuxSe
• Photoinduced nematic state in FeSe${}_{0.4}$Te${}_{0.6}$
• Time-Resolved Photoemission Spectroscopy of Quantum Materials Using High Harmonic Generation: Probing Electron-Phonon Interactions and Non-Equilibrium Dynamics