Studying the electronic structure of heavy fermions and 2D electron systems by means of angle-resolved photoemission spectroscopy

Abstract

In this project, we propose the study and characterization of electronic structure and Fermi surface of U-based and Ce-based heavy fermion compounds and 2D electron system (2DES) compounds in transition-metal oxides by means of Angle-Resolve Photoemission Spectroscopy (ARPES) technique. ARPES is an advanced spectroscopy technique that enable us to study directly the angular dependence of band structure of solids and the evolution of electronic structure and Fermi surface as function of temperature or doping. Specifically, it will be studied the heavy fermion compounds URu2Si2, Ce2MIn8 family (M = Rh, Ir) and some doped samples. The first compound is very interesting, because of its exotic states at low temperature, including an unconventional superconductive state near 1K and the so called hidden-order state that arises below 17.5 K and it is marked by development of a gap in the band structure at the Fermi level. The second compound, on the other hand, can present a variety of exotic ground states for different M elements, including unconventional superconductive, spin glass and the so called Non-Fermi Liquid behavior that arise in a vicinity of a Quantum Critical Point. These compounds can be driven from a state to another by means of an applied pressure or doping. In addition, we will study a system that present a 2D electron gas (2DEG) behavior, where an electron gas is free to move in two dimensions, but tightly confined in third dimension. The 2DEG compounds under study are formed by transition-metal oxides and can present exotic 2D phases of electron matter at oxides interfaces that have metal-insulator transition, superconductive or large negative magnetoresistance. To realize this project, we will measure these compounds by ARPES technique mainly in Soleil synchrotron at France. (AU)