Unveiling Unconventional Superconductor's phase diagrams via X-ray Spectroscopy

Marli R. Cantarino, Post-doc

 Electronic Structure, Magnetism and Dynamics Group, European Synchrotron Radiation Facility

Unveiling Unconventional Superconductor's phase diagrams via X-ray Spectroscopy

Abstract

Understanding the interplay between electronic structure, magnetism, and superconductivity in high-temperature superconductors remains a major challenge in physics. In this seminar, I present investigations on how adding small amounts of transition metals like chromium (Cr) and manganese (Mn) affects the properties of BaFe₂As₂, a material known for its potential to exhibit superconductivity. Using angle-resolved photoemission spectroscopy (ARPES), we explored how Cr and Mn doping change the electronic structure of these materials. While Cr modifies the electronic structure by introducing 'holes' (positive charge carriers), Mn does not, yet both suppress magnetic order similarly across the doping phase diagram without leading to superconductivity. We also used high-resolution resonant inelastic X-ray scattering (RIXS) to study magnetic excitations in Cr-doped BaFe₂As₂, revealing that these excitations become softer along two high-symmetry directions as Cr content increases. These findings help us understand why superconductivity does not emerge in these materials and how magnetic and electronic properties are interconnected.

Short Bio/CV

Marli R. Cantarino received her Ph.D. from the Universidade de São Paulo (Brazil) in 2023. She is currently a postdoctoral researcher at the European Synchrotron Radiation Facility (ESRF), where she conducts research using synchrotron-based spectroscopy techniques, with a focus on resonant inelastic X-ray scattering (RIXS), and provides technical support for external user operations. Her research focuses on strongly correlated electronic systems, low-dimensional spin systems, unconventional superconductivity, and complex phase diagrams. During her Ph.D., she gained expertise in surface science techniques, including ultra-high vacuum sample preparation, scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and angle-resolved photoemission spectroscopy (ARPES).