The reduction of dimensionality in bulk magnetism is due to the existence of a hierarchy of interactions, i.e. the magnetic coupling is much stronger in one or two spatial directions than in the remaining ones. This can lead to 2D, 1D (spin chains) or even 0D (single molecule magnets) magnetic arrangements, which are model systems for studying cooperative magnetic phenomena in presence or absence of long-range magnetic ordering. In particular, additional ingredients such as magnetic frustration or quantum effects induce exotic ground states (e.g. spin liquid state) dressed with excitations that may have no counterpart in conventional 3D magnets (e.g. spinons) and with specific defects (0D or 1D domain-walls).
Experimentally, the systems we are interested in are oxide compounds, but also molecular magnets in which the magnetic topology can be designed thanks to the versatile arrangement of molecular building blocks. We study their magnetic properties using specific instrumentation down to very low temperatures (<100 mK magnetometry and specific heat) as well as large scale facilities (neutron scattering and synchrotron X-ray). This allows us to probe precisely their unconventional phase diagram and the associated excitations, as a function of magnetic field and temperature.
Members of the team
Molecular magnets from 0D to 3D : Quantum tunneling, spin dynamics, …
Quantum spin chains : Entanglement, excitations, influence of 3D coupling…
Effect of strong spin-orbit coupling in spin chains.