X-ray diffuse multiple scattering with high flux synchrotron sources: applications in thermoelectrics and topological insulators

• Grant number: 22/09531-8
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2022
• End date: October 31, 2024
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Sérgio Luiz Morelhão
• Grantee: Maurício Bastos Estradiote
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

A little known phenomenon called diffuse multiple scattering (DMS) can be observed when the diffuse scattering from inside of a crystal stands out from diffuse scattering made at the entrance surface of the X rays on the material.The general diffuse scattering originates from the inhomogeneities of the crystal lattice, hence the need to use beams with cross sections small enough to minimize the scattering on the surface, region with large inhomogeneities. The diffuse scattering arising from inside the crystal, when undergoing rescattering by Bragg's planes, gives rise to the DMS. Imaging Bragg's cone with monochromatic radiation is a unique phenomenon and, in principle, capable of monitoring the 3D structure of a crystal under conditions of limited goniometry, i.e. with few rotational degrees of freedom of the sample. In this project, tools of graphical analysis previously developed (scientific initiation project of the candidate), and experiments with high flux synchrotron beams will be extensively employed in challenge studies with the aim both of sedimenting the possibilities of the DMS imaging technique as in understanding the structure of technological materials. First, quantify the diffuse scattering produced by anharmonic vibrations in thermoelectrics of the skutterudite class, characterize contributions to DMS of epitaxial structures combining topological insulators and magnetic materials, and finally to determine the resolution of DMS images in monitoring distortions in crystal lattice parameters under extreme conditions.