Seminar: Structural and dynamic study of several magnetic systems by means of Neutron Resonant Spin Echo techniques

“ZETA” is a Neutron Resonant Spin Echo (NRSE) option which is currently installed on the thermal triple-axis spectrometer IN22 (CRG beamline at Institut Laue Langevin). To illustrate its flexibility and capabilities, I will present some results which have been collected during the last three years by making use of high resolution diffraction and spectroscopy techniques, as well as cutting-edge Time-Resolved Polarized Neutron Reflectometry (TRAC-PNR).
Three “model” systems will be presented. In a first part, I will focus on the BaM2(XO4)2 (M = Co, Ni ; X = As, P)-family which members are good prototypes of quasi-2D magnets. The effect of magnetic ordering on lattice constants is easily revealed thanks to Larmor diffraction. Moreover, the thermal evolution of optic magnon lifetime in BaNi2(PO4)2 is shown to be strongly affected by the presence of defects in its structure, raising questions about the collision rate of such excitations in non-ideal systems. Then, the spin-chain and -ladder compound Sr14Cu24O41 will be addressed. I first focus on the study of the sharp inelastic peak associated with the spin gap in the ladders spectrum and introduce a method capable of showing directly the degeneracy of the associated spin transition. An attempt to evaluate its intrinsic linewidth will be described and the effect of different charge ordering processes on the material crystallographic structure. Ultimately, I show how we can adapt the existing instrumentation to perform TRAC-PNR experiments, using the so-called MIEZE principle, for the study of a magnetic multilayer which can present interesting properties for applications in spintronics.

Date

11.06.2012

Time

14:45–15:45

Place

Physics HS3

Garching, Garching, Deutschland

Speaker

N. Martin, Forschungsneutronenquelle Heinz Maier-Leibnitz, Technische Universität München

Organizers

TUM/FRM II

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