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Séminaire MCBT

vendredi 12 Février à 14h00,
Salle Louis Weil, E424

Orateur : Arno Hiess (ESS Lund Sweden)
"Future scientific possibilities for the investigation of microscopic magnetic properties provided by the innovative instrumentation at the European Spallation Source (ESS)"

Abstract

The ESS science drivers include soft condensed matter research, life science, studies of magnetic and electronic phenomena, chemistry of materials, energy research, engineering materials and geosciences, archaeology and heritage conservation, as well as fundamental and particle physics. ESS’s high brightness allows to probe weak signals, study phase transitions and systems that change over time, or to measure within a small volume. This last ability is particularly useful for real-world heterogeneous samples or for materials for which only small sample quantities are available or can be used.

In this presentation I will illustrate scientific possibilities by some recent neutron scattering investigations performed at several existing neutron sources including inelastic neutron scattering (INS) experiments on actinide-based superconductors. INS has been of particular importance to appreciate the interrelation of magnetism and superconductivity by studying the microscopic spin dynamics in momentum and energy space. As in the case of high temperature superconductors, the spin dynamics changes on entering the superconducting state in cerium- and uranium-based intermetallic superconductors : a gap opens at low energies and inelastic neutron scattering experiments reveal that an increased magnetic intensity is present above the gap, forming in most cases a sharp inelastic peak (so -called ‘spin resonance peak’). Its momentum space dependence is related to the symmetry of the superconducting order parameter but its relevance for the pairing mechanism is still subject of debate.

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