Quantum Materials

Exotic collective quantum physics is what we are looking for: entangled ground states, excitations with fractional quantum numbers, quantum criticality. Real materials are where we find it. However elegant a model Hamiltonian may be on paper, it becomes experimental physics only when it is embodied in an actual chemical compound, one that can be synthesized, grown as a crystal, cooled in a cryostat and probed in a measurement. Our quantum magnets are precisely such embodiments: real-world materials, not some abstractions in the inflamed mind of a theoretical physicist.

The most informative experiments on quantum magnets are those done on single crystals. This is obviously true for any measurements in applied magnetic or electric fields: fields applied along which crystallographic direction? Single crystals are equally important for neutron scattering experiments, where we measure correlations and excitations as a function of momentum transfer. Momentum is a vector, so again: momentum along which crystallographic direction? Neutron experiments, especially spectroscopy, impose an additional requirement: the crystals need to be huge. A chemist may call a 1 mg single crystal "large", but for inelastic neutron scattering we need gram-sized crystals!

Making single crystal samples of quantum magnets is therefore the necessary first step in almost every study we undertake. We use a variety of growth techniques, including wet chemistry methods and high-temperature furnace growth. Many of our single crystal samples are unique in the world.

The pages in this section form a virtual "museum" of the materials we have grown and studied over the years; browse the collection through the menu, where the compounds are grouped by the magnetic model they realize. Each page shows the crystal structure, the magnetic model, and what we learned from the material.