Unconventional phases of actinide compounds under extreme conditions

Abstract

Understand the behavior of an interacting or correlated electrons system in metallic compounds remains one of the major challenges in modern physics. A concept that has attracted considerable attention by the scientific community is the quantum criticality, which can occur by reducing the temperature characteristic of a second-order phase transition through the absolute zero using some external parameter such as hydrostatic pressure, chemical substitution, or magnetic field. In the vicinity of a quantum critical point new fundamental states in itinerant systems are established, which includes unconventional forms of superconductivity and magnetism. In this postdoctoral project we propose to investigate the magnetic, electronic and structural properties of uranium based compounds near to quantum critical points. We will use X-ray magnetic circular dichroism technique under extreme conditions of pressure and temperature to study the behavior of the 5f, 6d orbitals and their hybridizations. Changes in structural properties and distance between neighbor atoms will be followed by X-ray diffraction and extended X-ray absorption fine structure measurements. This complete set of information will allow us to elucidate the mechanisms that govern the competition between ferromagnetism and superconductivity in uranium compounds and can open a perspective to better understand the unconventional superconductivity.