Abstract

Interfaces between materials have led to revolutionary discoveries. When precisely crafted at the atomic scale, proximity effects, reduced dimensionality and symmetry breaking compete at interfaces to bring out quantum phenomena and unforeseen functionality. In this talk I will discuss examples from my work where heteroepitaxial interfaces play a pivotal role in the aggregate response of a system. These include: 1. Dielectric superlattices consisting of precisely integer molecular layers of titanate phases - CaTiO3, BaTiO3 and SrTiO3, where the symmetry of the superlattice and hence its electronic response was controlled by the sequence of interfaces built into the structure. 2. Mixed-valent manganites, where ordered pseudo alloys constructed through digital superlattices to have the same average doping as their random alloy counterparts albeit with removed structural disorder, resulted in modified electronic and magnetic properties. 3. Extreme heteroepitaxy between SrTiO3 and (001) Si avoiding the formation of an amorphous interfacial SiO2 layer where a commensurately strained SrTiO3 film and thus a strain induced ferroelectric directly on silicon was obtained. Through these examples, I will show how such nanoscale sample design, when carefully combined with other techniques, can be used to probe basic and applied physics.

(Everyone is welcome to attend)

Dr. Maitri P. Warusawithana is a candidate for the Experimental Condensed Matter Physics Position.