Probing electronic properties to engineer new materials (Nanowerk News) The scientific community is gearing up for the ultimate challenge -- to race the speed of light. In this quest, they are tinkering with the electronic and magnetic properties of new materials to improve the performance and capabilities of logic, memory and energy devices for next-generation technology.

During the 65th AVS International Symposium and Exhibition, being held Oct. 21-26, in Long Beach, California, Alexander Gray will discuss his work using soft and hard X-ray angle-resolved photoemission spectroscopy (ARPES) to explore the depth- and momentum-resolved electronic structure of quantum materials and nanostructures. His presentation will be given during the session entitled Novel Trends in Synchrotron and FEL-based Analysis.

Hard X-ray photoemission builds on X-ray photoelectron spectroscopy. It uses high-energy X-rays to probe matter for its electronic structure. Despite its success over the past half-century, photoelectron spectroscopy has earned the reputation of being limited to probing the surface of matter. The addition of momentum resolution allows scientists to map the dispersion of electronic bands to resolve the true bulk electronic properties of crystalline solids. With this information, scientists can characterize the nanoscale evolution of electronic properties as a function of depth. Their work could be used to design matter for future applications.

For many technologically promising new materials, such as topological insulators, Weyl semimetals, strongly correlated oxides and high-temperature superconductors, electronic and magnetic properties can vary dramatically as functions of depth and proximity to other materials, said Gray, an assistant professor at Temple University. By going to higher excitation energies, we gain access to the missing information about the deeper layers, buried interfaces and the true bulk electronic structure of the material.

Gray and his colleagues use both low- and high-energy X-ray photoemission to extract comprehensive information about the electronic structure of a material. With these tools, they can look beneath the surface and map out the true bulk electronic structure of materials as a function of energy and momentum.

Grays team studies the surface, interface and bulk electronic properties of a wide range of materials and structures. By characterizing electronic properties on three levels, it may be possible to engineer new materials. Gray points to the ability to tailor materials that respond to external stimuli, such as an electric field, temperature or sunlight. Information is power, Gray said. This research is the first step, the cornerstone that will allow us to understand the fundamental physical properties of new materials.