Pressure-induced exotic states in rare earth hexaborides

Abstract

Rare earth hexaborides compounds belong to a material class which presents remarkable properties such as high constant resistivity at low temperatures, heavy fermium behaviors, unusual superconductivity, along others that make them fascinating materials for physical research in both applied and fundamental levels. These phenomena are related to the non-trivial topology found in this compounds due to rare earth "d-f" electrons orbitals hybridization. However, the way of defining the topology of such materials causes intensive literature debates, essentially due to the difficulty to directly determine the degree hybridization between electronic levels and its relation with macroscopic properties. The aim of this project is to study electronic and structural properties of RB6 (R= Yb, Eu) materials under extreme conditions, such as high pressures and low temperatures, using synchrotron radiation techniques. Using X-ray absorption near edge structure (XANES), X-ray magnetic circular dichroism (XMCD) and x-ray diffraction (XRD) it will be possible to probe cristalline and electronic structure and also obtain information about the magnetism of samples under high pressures and low temperatures. This complete set of structural, electronic and magnetic information as a function of crystal lattice contraction tends to significantly help in the elucidation of mysteries that surrounds hexaboride materials and will serve as a guide to studies of further materials with similar structures/properties.Beyond the scientific objectives already described, taking full advantage of the unique experimental conditions that will be available at the new Brazilian Synchrotron Light source, Sirius, we intend to develop the instrumentation to implement X-ray resonant magnetic scattering (XMRS) under high pressures technique at the EMA beamline, creating a new way to probe magnetic materials in Brazil. (AU)