Sanu Mishra and Ilya Sheikin, LNCMI Grenoble, Tobias Förster, HLD Dresden, and Alix McCollam, HFML Nijmegen. Rare-earth-based materials are now widely recognized as an ideal playground for exploration of the fascinating physics that develops around a quantum critical point (QCP). In Ce-based compounds, such a QCP typically separates an antiferromagnetic [...]
Toni Helm, HLD Dresden. Strongly correlated electron materials, in particular heavy-fermion compounds, offer a huge playground for research on fundamental concepts in condensed-matter physics. The antiferromagnetic (AFM) metal CeRhIn5 provides a textbook example of quantum criticality in a heavy-fermion system: Pressure suppresses local-moment AFM order and induces superconductivity in a [...]
Mateusz Dyksik, Wroclaw University and Paulina Plochocka, LNCMI-Toulouse. Two-dimensional organic-inorganic halide perovskites have generated tremendous interest in the field of optoelectronics for applications in low-cost and efficient light absorbers and emitters. Similar to their three-dimensional (3D) ancestors, the layered perovskite derivatives exhibit promising performance in photovoltaic and lightemitting devices, [...]
David Leboeuf and Marc-Henri Julien, LNCMI-Grenoble. Extensive studies of cuprate superconductors have shown that, after three-dimensional Néel order disappears upon hole doping (p), there are still remnants of spin order at low temperature in the form of a glass-like freezing of incommensurate antiferromagnetic correlations. However, the importance of the [...]
Uli Zeitler, HFML Nijmegen. The fractional quantum Hall effect (FQHE), observed in low-temperature magnetotransport experiments in two-dimensional (2D) electron systems and caused by the electron-electron interaction, can be regarded as an ultimate proof of device quality in terms of quantum mobility, homogeneity, and low residual impurities. Until recently, the observation [...]
Sergei Zvyagin, HLD Dresden. Spin systems with honeycomb structures are attracting a great deal of attention, in particular in connection with the famous Kitaev-Heisenberg model. This model predicts a variety of magnetic phases, ranging from the conventional Néel state to a quantum spin liquid, with the spin dynamics determined [...]
William Knafo, LNCMI-Toulouse, Shingo Araki, Okayama University, and Daniel Braithwaite, CEA-Grenoble. The mystery of the hidden-order (HO) phase in the correlated electron paramagnet URu2Si2 is still unsolved. To address this problem, one strategy is to search for clues in the subtle competition between this state and neighboring magnetically ordered [...]
A. Akrap, University of Fribourg, A. V. Pronin, Universität Stuttgart, and M. Orlita, LNCMI-Grenoble. Experiments have demonstrated many gapless electronic phases with conical bands. These phases exist within diverse classes of systems comprising graphene and many different topological materials. Low-energy excitations in such conical bands somewhat resemble truly relativistic [...]
Owen Moulding and Sven Friedemann, University of Bristol. TiSe2 features a charge density wave (CDW) driven by condensation of excitons, i.e., pairs of electrons and holes, alongside electronphonon coupling. The CDW transition at 202 K gaps out most of the Fermi surface. Quantum-oscillation measurements at the HFML Nijmegen provide [...]
Matthew Bristow, Amalia Coldea, University of Oxford and William Knafo, LNCMI-Toulouse. CaKFe4As4 belongs to a new family of 1144 iron-based superconductors. It is a clean and stoichiometric superconductor with a relatively high critical temperature of 35 K. This system lacks long-range magnetic order or a nematic electronic state at [...]