Light Control of Superconductivity

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Strong electric field transients at terahertz frequencies can be used to control the electronic properties of high-temperature superconductors. In a series of experiments we demonstrated that the superconducting response of high-Tc cuprates and of some alkali-doped fullerides can be transiently enhanced by stimulating with light some specific vibrational degrees of freedom. In addition, resonant excitation of Josephson Plasma modes at millimeter wavelengths has also been shown to be a powerful tool to drive exotic dynamics in layered superconductors.

- Light-induced superconducting-like properties in high-Tc cuprates
- Josephson Plasmonics
- Possible light-induced superconductivity in K3C60 at high temperature

Coherent many body dynamics

The interplay of correlations that leads to electronic order in the Mott transition or Charge Density Wave state is one of the key challenges in correlated electron systems. It gives rise to a large variety of different ground states ranging from highly unconventional (“bad”) metals to charge density wave states or superconductivity.

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Phase control in complex oxides

The ground states of strongly correlated electron systems are stabilized by the complex interaction of electronic, magnetic and lattice degrees of freedom. Their nonlinear physics promote a large susceptibility of their macroscopic electronic and magnetic to external perturbations.

The stimulation with light can perturb a stable ground state and induce transient metastable phases - with dramatic rearrangements in the structural, electronic and magnetic properties. These optically driven states are typically ´hidden´ phases, not found in the equilibrium phase diagram. Of particular interest for our group is the selective excitation of one single (vibrational) degree of freedom on low energy scales, in stark contrast to excitation at visible or near-IR wavelengths mostly heating up the electronic systems.

- Light-induced insulator-metal transitions and magnetic switching in manganites
- Ultrafast phase control across oxide hetero-interfaces

Nonlinear Phononics

Our group has demonstrated that the selective excitation of infrared-active lattice vibrations is a powerful tool for the control of quantum matter. Insulator–metal transitions, magnetic switching and even high-temperature superconductivity have been induced in this way. Crucially, such vibrational stimulation makes possible the control of solids in their electronic ground state, and the reduced dissipation of direct lattice excitation makes it also attractive for applications in functional material control.

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