Superconductivity and Novel Properties of Light Element Materials

Under extreme conditions of high pressure and/or temperature, the properties of materials may change dramatically, leading to interesting new phenomena of fundamental interest in physics. In addition, the theory and modeling of the behavior of solids and liquids as a function of density and temperature has relevance to planetary science and for technological applications. Therefore, high-pressure research offers many unexploited opportunities for first-principles theorists. Room temperature superconductivity has been a dream for many years. Recently, room-temperature superconductivity in a carbonaceous sulfur hydride has been reported at high pressure in an unknown C-S-H phase (Dias, et al., Nature, 586, 373-377 (2020)). This discovery of superconductivity at ~15C is ground-breaking, albeit this new material must be under extreme pressures on the order of 200 GPa. Room temperature superconductivity is not only a fascinating goal for basic research, but it will also have tremendous impact on a number of technologies from levitating trains to magnetic resonance imaging (MRI) devices, which are used widely to see inside the human body, to detect tumours and other diseases I plan on working on light-Z materials such as lithium. Lithium is considered to be more promising materials for many physical properties. In particular, I plan to explore the finite temperature stability and superconductivity of the phase diagram of Li at high pressure, above 200 GPa. This will be required to study the physical properties of the unique and complex structures that Li have at such high pressure. The superconductivity of these phases of solid Li has not been studied before. I propose to use various structure prediction techniques including first-principles based evolutionary algorithms, and the Molecular Dynamics (MD) based method I am currently developing. My approach to structure searching is based on the idea that the short range interactions between atoms in the liquid state, when not far above the melting curve, provides formal signatures of the solid phase, which makes it more efficient and suitable for identifying the structures that are stable only at finite temperatures. This method will offer a huge opportunity to study effectively the phase diagram of Li at finite temperatures, especially if the lattice dynamics are important for the stabilization some of the structures.