Emergent phenomena in d-electron systems probed by synchrotron-based techniques

Abstract

d-electron systems are an attractive field of study due to their rich variety of emergent phenomena, such as in high-temperature superconductivity (high-Tc), Mott insulators, and multiferroicity, which generally arise from strong electron correlation. One such example is the high-Tc cuprate family La2-xBaxCuO4. For x = 0, the Coulomb repulsion is so strong that these compounds are antiferromagnetic insulators at low temperatures. Hole doping suppresses the magnetic order and leads to the coexistence of superconductivity and charge density waves, the latter giving rise to weak superlattice diffraction peaks. Based on this scenario, we aim to take advantage of the high intensity of synchrotron X-ray diffraction to probe the interplay of superconductivity and charge ordering of La2-xBaxCuO4 (x = 0.125 and 0.135) under uniaxial strain. Another interesting case is the role of moderate Coulomb repulsion and strong spin-orbit coupling of 5d Re electrons in Ca2-xYxMnReO6 (x = 0.0 and 0.3), turning these compounds insulators and highly non-collinear antiferromagnets. Taking advantage of the energy tunability of synchrotron facilities, we also intend to explore the element-specific Mn and Re magnetism in this family. In fact, through resonant magnetic X-ray diffraction, X-ray Absorption Near Edge Structure (XANES), X-ray Magnetic Circular Dichroism (XMCD) and Resonant Inelastic X-ray Scattering (RIXS) measurements on Re L2,3 edges, the nature of the magnetic moments and Jeff ground states may be probed. (AU)