Oxide-based Heterointerfaces

Formation of a two dimensional conducting interface between two perovskite insulators was first reported in 2004. This unexpected result was related to internal polarization, defect structures and polarization discontinuity. In 2006 it was reported for the first time that the conductivity of the hetero-interface could be switched between two states by application of an external field. This memory effect opened the pathway for revolutionary new technologies that depend on different physical effects than semiconductor based memories. Our research focus is on identifying the effects of defects on the properties of interfaces. The five major sections of investigation will be; (i) processing and film characterization, (ii) electrical characterization of the interfaces, (iii) first-principles modeling, (iv) high temperature effects and (v) proof of concept applications. The focus is on seven different parameters: (i) Composition of the film, (ii) strain, (iii) interface composition, (iv) anisotropy, (v) surface conditions, (vi) electrodes, and (vii) temperature. These parameters are not isolated from each other and cross-cutting effects are also investigated.

Our research approach aims to not only identify the origins of charge at hetero-interfaces but also define the quantifiable role of structural and compositional factors, such as defects, dipoles, domain boundaries and strain, on the electrical properties of the interface. Quantitative identification of each parameter is required to understand high temperature behavior, as well as to develop devices based on hetero-interfaces operational at extreme environments. 

Collaborators:

Walter Lambrecht (Physics Department - Case Western Reserve University)

Xuan Gao (Physics Department - Case Western Reserve University)

Marie-Helene Berger (Ecole De Mines - Paris, France)