My graduate work involves discovering, investigating, and understanding new materials. One class of materials, complex oxides, have well understood and useful bulk properties such as high-k dielectrics, magnetism and superconductivity. However, new exciting behaviors emerge when interfaces are created by epitaxially growing a thin film of one material on a bulk substrate. One example of a new and surprising behavior is the conducting interface that appears between the insulators lanthanum aluminate and strontium titanate.
To study these materials on a local scale I use a home-built scanning SQUID microscope in a dilution refrigerator. The dilution refrigerator allows me to make measurements at temperatures as low a ten millikelvin. The SQUID microscope is a flux sensor that can detect magnetic fields six orders of magnitude smaller than the earth's field (~10-11 T) and can resolve features as small as one one-hundredth the width of a human hair (~1 micron). (Photo by Steve Gladfelter)