Creating order through periodic driving: From novel topology in (artificial) graphene to superconductivity

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• Gregor Jotzu (Max Planck Institute for the Structure and Dynamics of Matter, Hamburg)
• Thursday 10 December 2020, 13:00-14:00
• https://bham-ac-uk.zoom.us/j/9115054257? pwd=UWJqaGZpZitLUVZHQkJGby9xU2dXQT09.

If you have a question about this talk, please contact Dr Hannah Price.

In general, periodically modulating an internal or external parameter of a complex system tends to create entropy and thereby destroys order. However, regimes can be found where the opposite happens. Starting from the controlled environment of ultracold fermionic atoms in optical lattices, I will show how a periodically oscillating force can used to cross a topological transition first predicted by Haldane. Here, the mechanism can be well understood using unitary Floquet theory. In the case of a real Graphene sample, the theoretical description becomes more involved owing to decoherence and the coupling to a reservoir. Nevertheless, we find that the light-induced Hall effect we observe using ultrafast transport measurements, is still remarkably similar to predictions based on simple Floquet theory. In real materials with strong interactions, the effects of periodic driving are usually more difficult to understand. I will present recent progress on experiments on A3C60 fullerides, where strong mid-infrared light pulses cause signatures of superconductivity to appear well above the critical temperatures for equilibrium superconductivity. The recent extension of this light-induced effect to nanosecond time-scales opens up a range of new observables. In particular, I will present ongoing work on using optical magnetometry in the sub-picosecond and sub-microtesla regime to probe the magnetic properties of light-induced states of matter.

This talk is part of the Theoretical Physics Seminars series.

This talk is included in these lists:

• Bham Talks
• Theoretical Physics Seminars
• What's on in Physics?
• https://bham-ac-uk.zoom.us/j/9115054257? pwd=UWJqaGZpZitLUVZHQkJGby9xU2dXQT09

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