Physics at the Interface
D. D. Sarma
Indian Institute of Science, Bangalore
In recent time, there is an increasing appreciation of cases where the sample properties are controlled by neither the volume nor surface, but by a sharp or diffused interface that is buried beneath the surface by several nanometres. There has been an enormous increase in the interest to understand the nature of such interface states in two distinct contexts, namely, complex core-shell type nanoparticles of semiconductors with extraordinary photoluminescence properties and bi- or multi-layer heterostructures with spectacular electronic and magnetic properties. Roles of such buried interfaces can be investigated meaningfully only by a handful of techniques, with the most direct information extractable from photoelectron spectroscopy with a variable hard x-ray source. I shall discuss some of the recently studied systems, including case studies on LAO-STO, MTJ and nanoparticle systems, where the dominant property of the sample is controlled by such interfaces and present results that clarify the role of the interface in giving rise to such properties.