Seminar: Neutron scattering studies of quantum magnets

by Bella Lake (Helmholtz-Zentrum Berlin)

Wednesday 17 Dec 2014, 15:00 → 16:00 Europe/Stockholm

Main building seminar room (European Spallation Source)

Bella Lake
Helmholtz-Zentrum Berlin für Materialen und Energie,
Technische Universität Berlin,
 
Quantum magnetism is the study of magnetic materials where quantum fluctuations are strong and give rise to exotic behaviours not found in conventional magnets. Quantum fluctuations arise in magnets which have some or all of the following ingredient – magnetic ions with low spin value that coupled by antiferromagnetic interactions into low-dimensional structures and/or arrangements where the interactions compete with each other or with local anisotropies. It is possible to make model materials engineered to exhibit specific quantum features which can then be investigated using neutron scattering. This presentation will discuss a number of different quantum magnets starting from the Heisenberg and Ising spin-1/2 antiferromagnetic chains with fractional spinon excitations, to coupled chains or spin ladders where gapped magnon-type spectra are observed. In 2 and 3-dimensions competition due to frustration provides the source of quantum fluctuations and examples of triangle, kagome and pyrochlore lattice will be discussed.