Introduction to Quantum Beam Science with Neutrons and X-rays: Applications to Thin Films and Surfaces

Speaker: Dr David Cortie
Affiliation: Australia's Nuclear Science and Technology Organisation (ANSTO)

Abstract

This presentation will introduce newcomers to the realm of quantum beam science, emphasising the use of muons, neutrons, and X-rays to understand material properties from atomic to macro scales. I will detail neutron beam techniques, showcasing the world-class capabilities at ANSTO. I will present a general pedagogical description rooted in quantum mechanics, culminating in the widely-used Born approximation. To demonstrate the practical value, specific multidisciplinary applications demonstrated on our beamlines will include:

•            Neutron tomography of fossilised placoderms from Western Australia, i.e., “a dinosaur heart” [1]

•            Resolving the magnetic structure of antiferromagnetic oxides with atomic precision [2]

•            Clustering of charged colloidal particles in the microgravity environment of space [3]

•            Measuring vibrations, including phonons, in solids and liquids “beyond the Debye law” [4]

•            Identifying how the COVID-19 spike protein binds to High-Density Lipoproteins [5] *

In the second part of the talk, I will introduce “beyond-Born” techniques for studying nano-scale thin films, surfaces, and metastructures using evanescent neutron waves subject to strong dynamic scattering. I will demonstrate how polarised neutron reflectometry can be used to study quantum materials, nanofilms, surfaces, superconductors (thickness 1-100 nm), and lithographically-patterned arrays (lateral feature size 30 nm-20 µm). I’ll briefly discuss how this technique is implemented experimentally at the Australian Centre for Neutron Scattering and how data is analysed using analytical and numerical solutions to the optical equations, the 1D Schrödinger equation, or the Distorted Wave Born  Approximation. I’ll present a scientific case study using X-ray and neutron reflectometry to study crystal-glass transitions at topological insulator surfaces, which elucidated a mechanism for “top-down” lithography of electronic properties.

References:

 1) K.Ttrinajstic, Science 377, 1311, (2022)

2) J. Bertinshaw, D. L Cortie, Physical Review B 89, 144422 (2014)

3) H. Miki et al.,  npj Microgravity, 9:33, (2022)

4) C. Stamper, D.L. Cortie, D. Yu, J. Phys. Chem. Lett. , 13, 3105–3111 (2022)

5) Y. Correa, A.P.Le Brun et al., J Colloid Interface Sci. 645, 627 (2023)

6) A. Bake, D.L Cortie et al. Nature Communications 14 (1), 1693 (2023)