Shedding light on insulators: How light pulses unfreeze electrons (Phys.org)
Electrons in oxides are often “frozen” by strong mutual repulsion, keeping the materials insulating. A collaboration led by EPFL (Lausanne Centre for Ultrafast Science – LACUS) with contributions from the Max Planck Institute for the Structure and Dynamics of Matter, the Helmholtz-Zentrum Berlin, the Paul Scherrer Institute in Villigen, the University of Basel, the University of California Davis, Elettra-Sincrotrone Trieste and the Flatiron Institute, has shown that ultrafast multicolored ultraviolet pulses can transiently unlock this state.
In nickel oxide (NiO), a charge-transfer insulator structurally related to high-temperature superconductors, the pulses reduce the energy cost for electrons to move between atoms, creating a fleeting metallic phase that lasts for hundreds of picoseconds. The reduction of electron repulsion scales linearly with light intensity, and the material always relaxes back to its insulating state on similar timescales.
The work highlights a new way to control correlated materials with light, opening prospects for ultrafast switches, optoelectronics and solar technologies.
Read the whole Phys.org article here.
