Oleksandr Zheliuk, HFML Nijmegen. Scientists from the University of Groningen, together with colleagues from HFML Nijmegen, the University of Twente, and the Harbin Institute of Technology (China), have discovered the existence of a superconducting state that was first predicted in 2017. In particular, they present evidence for a special variant [...]

Hannes Kühne, HLD Dresden. Two-dimensional (2D) spin systems with an XY anisotropy are known to undergo a Berezinskii-Kosterlitz-Thouless (BKT) phase transition at a finite temperature TBKT, which marks the binding of topological defects in vortex-antivortex pairs. So far, experimental efforts to probe a genuine BKT transition in bulk materials were [...]

Ramakanta Chapai, J. F. Mitchell and Ulrich Welp, Argonne National Laboratory, Vincent Oliviero, Maxime Leroux, LNCMI Toulouse. The recently discovered-kagome lattice compounds AV3Sb5 (A = K, Rb, Cs) show a fascinating interplay of superconductivity, charge density wave (CDW) order, and nontrivial topology of the electronic band structure. The CDW order [...]

Matija Čulo, Institute of Physics, Zagreb, Croatia and Nigel Hussey, HFML and University of Bristol, UK. High-temperature superconductivity is one of the biggest unsolved problems in condensed-matter physics, due to its unconventional superconducting (SC) pairing mechanism, which goes beyond the standard electron-phonon interaction. Many materials with such an unconventional SC [...]

Jan Wyzula and Milan Orlita, University of Fribourg and LNCMI Grenoble. Magnons, or quantized spin waves, are collective magnetic excitations in solids. These boson-like quasiparticles disperse with lattice momentum k, carry a fixed energy, and possess an integer spin or angular momentum Sz = ±1. Although magnons are optically active, [...]

Sergei Zvyagin, HLD Dresden. Antiferromagnetic materials with spin 1/2 and triangular-lattice structures are in the focus of modern quantum physics, in particular, in connection with Anderson’s idea of “resonating valence bond” states in frustrated spin systems. He proposed that the ground state could be a two dimensional (2D) fluid of [...]

Amirreza Ataei and Louis Taillefer, Université de Sherbrooke, Canada, Cyril Proust and David Vignolles, LNCMI-Toulouse. In certain materials called “strange metals”, the electrical resistivity follows a perfectly linear temperature dependence at low temperature, in contrast to the standard quadratic dependence expected from standard Fermi-liquid theory. Remarkably, it has recently been [...]

Amit Pawbake and Clément Faugeras, LNCMI Grenoble. Spin waves (magnons) in magnetically ordered solids – ferromagnets or antiferromagnets – are collective excitations of an ensemble of spins. They propagate in the solid and do couple to phonons of the host material to create new quasiparticles named magnon-polarons. This coupling is [...]

Uli Zeitler, Steffen Wiedmann, HFML Nijmegen and Sergio Pezzini, Istituto Nanoscienze-CNR Pisa. The quantum Hall effect (QHE), a paradigmatic phenomenon of twodimensional (2D) electron systems in high magnetic fields, typically occurs only at very low temperatures of a few kelvin. Under these conditions, lattice vibrations (so-called phonons) are suppressed and, [...]

Tino Gottschall, HLD Dresden. We are witnessing a great transition towards a society powered by renewable energies to meet the ever-stringent climate target. Hydrogen, as an energy carrier, will play a key role in building a climate-neutral society. Although liquid hydrogen is essential for hydrogen storage and transportation, liquefying hydrogen [...]