1. Laboratory for Quantum Magnetism, Institute of Physics of Complex Matter, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland, School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ, United Kingdom, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland, Institute for Numerical Research in the Physics of Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland, Rutherford Appleton Laboratory, Chilton OX11 OQX, United Kingdom, School of...