Unravelling dynamics in condensed matter with polarized neutron time-of-flight spectroscopy

Data de Início:

quinta-feira, 28 Abril, 2022 - 16:00

Palestrante:

Prof. Gøran Jan Nilsen, ISIS Neutron and Muon Source, UK

Local:

Auditório Abrahão de Moraes (com transmissão ao vivo)

Acesso:

Via Zoom: comunidade IF, verifique seu e-mail institucional para informações sobre a sala.
ou You Tube (acima ou em youtu.be/XLyqUy9KZYE)

Resumo:

Neutron time-of-flight spectroscopy is a powerful tool to survey structural and magnetic dynamics in condensed matter systems over broad ranges in time and space. It has therefore been applied to a similarly broad range of scientific problems, from proton motions in fuel cell materials to spin excitations in magnets and superconductors. In many of these cases, it is important to distinguish the different processes that contribute to the overall scattering – nuclear coherent, nuclear spin-incoherent, and magnetic – in order to disentangle the dynamics of interest from the rest. For example, in transition-metal based battery cathode materials, the weak scattering signal from ionic diffusion (spin-incoherent) coincides with stronger signals from phonons (coherent) and paramagnetic scattering (magnetic). This class of problem, and many others like it, can be solved using neutron polarization analysis, which uses the neutron spin-dependence of the scattering components to separate them.

In this talk, I will introduce the key concepts behind polarized time-of-flight spectroscopy, using its first successful implementation on the LET spectrometer at the ISIS facility in the UK as an example [1]. This will be followed by a review of several recent scientific highlights from the same instrument, including work on collective dynamics in D2O [2], diffusion of cyclohexane in a zeolite, ionic transport in battery cathode and electrolyte materials, and magnetic diffuse scattering in a frustrated magnet. I will conclude with some future perspectives for polarized time-of-flight spectroscopy, with particular emphasis on the opportunities presented by its implementation on high-resolution neutron spectrometers.

[1] G. Cassella et al., J. Phys.: Conf. Series 1316, 012007 (2019)

[2] A. Arbe et al., Phys. Rev. Applied 2, 022015(R) (2020)

Sobre o palestrante: Goran Nilsen is an instrument scientist at the ISIS Neutron and Muon Facility in the UK. He develops instrumentation to investigate structure and dynamics in condensed matter, as well as carrying out research on magnetic materials and ionic conductors.

Desenvolvido por IFUSP

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Unravelling dynamics in condensed matter with polarized neutron time-of-flight spectroscopy