Talks

Abstract: Geometric frustration in spin systems can lead to a variety of ground states and excitations. I will present neutron spectroscopy data and calculations for two very different copper-based quantum magnets. The former is copper oxide sulphate, hosting a kagome-like lattice, the latter strontium copper boride, a quasi-ideal realisation of the Shastry-Sutherland model. Although both systems exhibit strong geometric frustration, they behave very differently, with Cu2OSO4 having a magnetically ordered ground state and spin-wave modes, whereas SrCu2(BO3)2 displays an exact dimer-product singlet ground state and bound states of triplets as excitations.

Bio: Federico obtained his master's degree from Politecnico di Milano with a thesis on charge-density waves in cuprate superconductors carried out at the European synchrotron RIXS beamline. He later joined the Laboratory for Quantum Magnetism at EPFL as a PhD student. His research activity focuses on the study of quantum magnets using neutron spectroscopy.

Thermo-Electro-Magnetic Coupling in Functional Composite Materials 

A large fraction of global primary energy is dissipated as waste heat, motivating the search for materials that can directly convert heat to electricity via the Seebeck effect. Tin selenide (SnSe) is a leading thermoelectric candidate due to its ultralow lattice thermal conductivity and favourable electronic structure. Beyond conventional optimisation strategies such as doping or alloying, the incorporation of magnetic nanoparticles offers an alternative pathway to tune transport properties through thermo-electro-magnetic coupling.
We investigate SnSe-Fe3O4 nanocomposites as a platform to probe the interplay between electrons, phonons, and magnons in a thermoelectric matrix. Structural and transport characterisation reveal that Fe3O4 inclusions can both enhance and suppress performance metrics depending on composition, temperature, and processing history. Time-of-flight inelastic neutron scattering demonstrates pronounced broadening of SnSe optical phonons in the composites, beyond that expected from a simple superposition of the constituent spectra, suggesting additional scattering channels, potentially from phonon–magnon coupling.
In this presentation we highlight the complexity and tunability of multi-quasiparticle interactions in magnetic thermoelectric composites and provide new insights into strategies for controlling coupled thermal, electrical, and magnetic transport.

Abstract:  The talk will describe how several neutron techniques have provided deeper understanding as to how seeds from Moringa trees can be used to purify water.  Flocculation can be analysed using small-angle scattering.  Very high density flocs are observed.  The binding of the flocculating agent to different surfaces as regards structure and amount is found from neutron reflection measurements and this can guide the amount of material that is needed.  Recent small-angle scattering studies of perfluorocarbon surfactants have identified factors controlling assembly and reflection measurements show how seed protein might be exploited for remediation of contamination.

Professor Adrian R. Rennie

Adrian Rennie studied in Cambridge, UK where he also completed his PhD on self-diffusion in 

polymers. He has worked in Germany, France and the UK prior to moving to Uppsala University as 

Professor of Neutron Scattering in 2003 where he served as Director of the Neutron Research 

Laboratory at Studsvik and since 2013 as Director of the Centre for Neutron Scattering. His research 

interests have centred on understanding the properties of soft matter with recent work on colloidal 

dispersions, polymer composites as well as applications of scattering.