Complex Oxide Interfaces: A Path to Design New Materials

ABSTRACTHeterostructures composed of transition metal oxides with strong electron correlation offer a unique opportunity to design new artificial materials whose electrical, magnetic and optical properties can be manipulated by tailoring the occupation of the d-orbitals of the transition metal in the compound. This possibility is an implication of symmetry constraints at interfaces with the consequence of a reconstruction of the coupled charge-, spin-, and orbital states of the constituents and their interactions. Novel architectures can be constructed showing functions well beyond charge density manipulations determining the functionality of conventional semiconductor heterostructures. Success in this endeavor requires the mastering of technological prerequisites such as structurally as well as chemically controlled interface preparation down to atomic scales. Additionally, a fundamental understanding of the modifications of the electronic structure at the interface imposed by structural boundary conditions and consequently by the constituent’s orbital occupation is required. A path towards a new generation of electronic devices with multiple functionalities can thus be opened by exploiting the correlation driven interface phenomena. In this paper, the technological challenges and experimental realizations along this concept are described with an emphasis of growth techniques based on the pulsed laser deposition method. As a case study, results of investigations of YBa2Cu3O7/La2/3Ca1/3MnO3superlattices are compiled and the conclusions regarding the orbital manipulation at the interface are used to pave the way for orbital engineering of oxides with electronic structures similar to the cuprates in order to find novel ordered quantum states at the interfaces including magnetism and superconductivity.