It has been discovered that many collective phenomena such as high-temperature superconductivity, “colossal” magnetoresistance, and quantum criticality, which do not appear in simple semiconductors, are emergent in complex correlated electron materials (CMEs). Even more surprisingly, many fascinating properties emerge at surfaces, interfaces, and artificial heterostructures of CEMs, the materials beyond mother nature. “The challenge is to understand how such collective phenomena emerge, discover new ones, and to determine which microscopic details are important and essential.”
Correlated electron devices will involve the fabrication of thin films, superstructures and junctions. Virtually all electronic devices began with an understanding of interface barrier formation, electronic/magnetic structure, and control “the interface is the device”. Incorporating the diversity of physical properties of CEMs into devices needs to begin with a basic understanding. Knowledge of the surface/interface properties as well as the effects derived from broken symmetry and reduced dimensionality is vital if these devices are to be made to work at optimized functionality.
In this talk I will focus on the issue about how lattice distortion, defects/vacancies and other imperfection, can dramatically affect the electronic and magnetic properties at the surface and interface of few CEMs. I will discuss few emerging properties at the surface, interface and heterostructures of CEMs, such as ruthenates, Fe-based superconductors, etc., as examples to illustrate the issue.
Dr. Zhang received B.S. and M.S. degrees in physics from the Nanjing University of Science and Technology in 1982 and the Chinese Academy of Science in 1986, respectively. He was on the faculty of Shanghai Jiao Tong University between 1986 and 1989. He received his Ph.D. in physics from Syracuse University in 1994, spent 3 years as a postdoctal fellow at Oak Ridge National laboratory/the University of Tennessee prior to joining the Florida International University as a faculty member in 1998. Starting from 2009, he became a full professor in physics at Louisiana State University. He is also a visiting professor of the Institute of Physics, Chinese Academy of Science.