ABSTRACT

Many current forthcoming applications of magnetic materials involve heterostructures or alloys containing magnetic and non-magnetic elements. X-ray Resonant (Coherent) Scattering is the technique of choice to probe such phenomena thanks to its element-selectivity and spatial sensitivity.

In this presentation I will introduce the experimental set-up that we developed at SOLEIL and illustrate their capabilities. SEXTANTS [1] is a beamline of the SOLEIL synchrotron, covering the 50-1700eV energy range dedicated to soft x-ray scattering. The resolving power exceeds 10⁴ and maximum flux on the sample ranges from 1×10¹⁴ (100 eV) to 2×10¹³ (1000 eV) ph./s/0.1% bw. The beamline main objective is the investigation of the electronic and magnetic properties of solids using three scattering techniques: resonant inelastic x-ray scattering (RIXS), x-ray resonant magnetic scattering (XRMS) and coherent x-ray scattering (CXS), the last one including also imaging via Fourier transform holography (FTH) [2].

In the second part, several recent results obtained at SEXTANTS beamline will be presented, and in particular I will show that XRMS is the tool to study magnetic chirality as illustrated with two systems: on one hand, Pt/Co multilayers in which Dzyaloshinskii-Morya interaction (DMI) is a induced by the inversion symmetry breaking at the Pt/Co interfaces [3,4] and on the other hand, an investigation we have done of BiFeO₃ thin epitaxial layers [4,5] in which the “bulk” DMI plays a major role in its magnetic configuration and in particular in the stabilization of the antiferromagnetic cycloid.

In the last part I will present the latest development of resonant scattering and in particular how the use of the x-ray coherence available at modern light source allow nowadays to image the sample with a spatial resolution of few tens of nanometers and a time resolution ranging from ns down to fs timescale.

[1] M. Sacchi et al., Journal of Physics: Conference Series 425 (2013) 072018

[2] S. Eisebitt et al., Nature, 432, 885 (2004).

[3] J.Y. Chauleau, et al., Phys. Rev. Lett. 120, 037202 (2018).

[4] W. Legrand et al., submitted and https://arxiv.org/abs/1712.05978

[5] I. Gross et al., Nature 549, 252 (2017)

[6] J.Y Chauleau et al., in preparation