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 [...]

Alessandro Surrente, Wroclaw University of Science and Technology, Paulina Plochocka, Wroclaw University of Science and Technology and LNCMI Toulouse. The synthesis of colloidal nanocrystals with near-unity photoluminescence (PL) quantum yields has vastly extended the potential of metal-halide perovskites for solid-state lighting and display applications. It is possible to template the [...]

Elena Blundo, Antonio Polimeni, Sapienza University of Rome, Adam Babiński, University of Warsaw, and Peter Christianen, HFML Nijmegen Strain plays an important role in two-dimensional (2D) semiconductors. Thanks to their all-surface nature, these 2D materials feature an extraordinary capability to bear mechanical deformations without fracturing. This resilience to stress reveals [...]

J. Chang, Zürich University, M. Ichioka, Okayama University, D. Campbell, D. Le Boeuf, LNCMI Grenoble. In the physics of correlated electron systems, van Hove singularities play a key role. These are points in the band structure where the density of states is singular. When the Fermi level is tuned towards [...]

Denis Gorbunov, HLD Dresden. Optical excitations in solids require conservation of momentum and energy. This applies also to magnetic excitations, when a magnon with a given momentum and energy is created / annihilated by absorbing / emitting a photon. The small photon momentum typically confines possible excitations close to the [...]