We are pleased to announce two new publications.

First, our paper about the enhancement of the ferromagnetism of YBCO nanoparticles under strong-coupling has been accepted in Nano Letters and is now available in open access. Making use of cooperative strong-coupling, we measured a strong ferromagnetism even at room temperature, that competes with superconductivity below the Tc of YBCO. Thanks and congratulations to our collaborators from IPCMS !

Second we published a “Feature Article” in Physics Today, in collaboration with Jérôme Faist from ETH Zürich, dealing with the control of new properties in materials via the hybrid light-matter states created in optical cavities.

To read by the fireside during this rainy and cool spring !

Our latest results have just been accepted for publication in Nature Communications. In this work we strongly couple the exciton of cyanine dye J-aggregates to an optical mode of a Fabry-Perot (FP) cavity, and achieve an enhancement of the complex nonlinear refractive index by two orders of magnitude compared with that of the uncoupled condition. Moreover, the coupled system shows an ultrafast response of ~120 fs that we extract from optical cross-correlation measurements. The ultrafast and large enhancement of the optical nonlinar coefficients in this work paves the way for exploring strong coupling effects on various third-order nonlinear optical phenomena and for technological application. The paper is now accessible in Open Access on Nature Communications website and on our publications page.

Vibrational strong coupling (VSC) has recently been shown to change the rate and chemoselectivity of ground state chemical reactions via the formation of light‐matter hybrid polaritonic states.Our recent observation that vibrational mode symmetry has a large influence on charge transfer reactions under VSC suggested that symmetry considerations could be used to control other types of chemical selectivity. We thus explored the stereoselectivity of the thermal electrocyclic ring‐opening of a cyclobutene derivative, a reaction which follows the Woodward‐Hoffmann rules, under VSC. The direction of the change in stereoselectivity depends on the vibrational mode that is coupled, as do changes in rate and reaction thermodynamics. All this is summarized in a new publication, resulting from a collaboration with Joseph Moran‘s group, that just appeared in Angewandte Chemie in Open Access, but also in our publication page.