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Université de Fribourg

Total Angular Momentum Dichroism of the Terahertz Vortex Beams at the Antiferromagnetic Resonances

Sirenko, Andrei A. ; Marsik, Premysl ; Bugnon, Laurent ; Soulier, Mathias ; Bernhard, Christian ; Stanislavchuk, T. N. ; Xu, Xianghan ; Cheong, S.-W.

In: Physical Review Letters, 2021, vol. 126, no. 15, p. 157401

Terahertz vortex beams with different superposition of the orbital angular momentum $l={\pm}1$, ${\pm}2$, ${\pm}3$, and ${\pm}4$ and spin angular momentum ${\sigma}={\pm}1$ were used to study antiferromagnetic (AFM) resonances in TbFe$_3$(BO$_3$)$_4$ and Ni$_3$TeO$_6$ single crystals. In both materials we observed a strong vortex beam dichroism for the AFM resonances that are split in ...

Université de Fribourg

Experimental tuning of transport regimes in hyperuniform disordered photonic materials

Aubry, Geoffroy J. ; Froufe-Pérez, Luis S. ; Kuhl, Ulrich ; Legrand, Olivier ; Scheffold, Frank ; Mortessagne, Fabrice

In: Physical Review Letters, 2020, vol. 125, no. 12, p. 127402

We present wave transport experiments in hyperuniform disordered arrays of cylinders with high dielectric permittivity. Using microwaves, we show that the same material can display transparency, photon diffusion, Anderson localization, or a full band gap, depending on the frequency ν of the electromagnetic wave. Interestingly, we find a second weaker band gap, which appears to be related to...

Université de Fribourg

A literal elytral rainbow: tunable structural colors using single diamond biophotonic crystals in Pachyrrhynchus congestus weevils

Wilts, Bodo D. ; Saranathan, Vinodkumar

In: Small, 2018, vol. 14, no. 46, p. 1802328

The brilliant colors of many insects arise from the interference of incident light with complex nanostructured biomaterials that are present in their cuticle. Here, the rainbow‐colored spots on the elytra of a snout weevil, Pachyrrhynchus congestus pavonius (Coleoptera: Curculionidae), are investigated using synchrotron small‐angle X‐ray scattering, scanning electron microscopy,...

Université de Fribourg

Time- and angle-resolved photoemission spectroscopy of solids in the extreme ultraviolet at 500 kHz repetition rate

Puppin, M. ; Deng, Y. ; Nicholson, Christopher W. ; Feldl, J. ; Schröter, N. B. M. ; Vita, H. ; Kirchmann, P. S. ; Monney, Claude ; Rettig, L. ; Wolf, M. ; Ernstorfer, R.

In: Review of Scientific Instruments, 2019, vol. 90, no. 2, p. 023104

Time- and angle-resolved photoemission spectroscopy (trARPES) employing a 500 kHz extreme-ultraviolet light source operating at 21.7 eV probe photon energy is reported. Based on a high-power ytterbium laser, optical parametric chirped pulse amplification, and ultraviolet-driven high-harmonic generation, the light source produces an isolated high-harmonic with 110 meV bandwidth and a flux of...