Colloquium: Two-Dimensional Approach of Correlated Oxides

ABSTRACT

Due to the nature of synergetic and delicate couplings of different degrees of freedom, it is anticipated that the quantum states in transition metal oxides would be revolutionized by reducing dimensionality and breaking symmetry through heterostructure architecture. In this talk, I will present some recent results from cuprate and ruthenate heterostructures toward two-dimensional limit. Specifically, by atomically layer-by-layer growth with oxide MBE, it is observed that La2-xSrxCuO4 (x = 0.15) thin films maintain superconductivity down to 2-unit cells of thickness but quickly reach the maximum superconducting transition temperature at and above 4-unit cells. By fitting the critical magnetic field, it shows that the anisotropy of superconductivity increases with decreasing film thickness, indicating that a crossover from weak three- to two-dimensional character. Furthermore, I will emphasize that constructing well defined interfaces with atomic-level precision is crucial to understand the intrinsic properties of oxide heterostructures.  By using SrRuO3/SrTiO3 interface as an example, I will discuss the important role played by interface structure in the electronic and magnetic properties of the heterostructure in atomic-scale limits.

BIOGRAPHY

Jiandi Zhang, received his M.S. degree from Chinese Academy of Sciences in 1986, and Ph.D. degree from Syracuse University in 1994. He was in University of Nebraska, University of Tennessee, and Oak Ridge National Laboratory as a postdoc/stuff scientist between 1995 and 1998. From 1998 to 2008, he worked in Florida International University From 1998 to 2008, he has worked in Florida International University as an assistant and associated professor. In 2008, he moved to Louisiana State University as a tenured full professor. In 2021, he joined the Institute of Physics, Chinese Academy of Sciences as a Distinguished Professor at the State Key Laboratory for Surface Physics. He has received US NSF Career Award and is a fellow of American Physics Society.