We determine the origins of these phenomena and explore innovative applications for superconductivity and novel smart materials.
The first focuses on discovery and control of novel physical phenomena in superconductivity, magnetism and vortex matter that can emerge through tailored heterogeneity induced by particle irradiation, magnetic texture and thermal hotspots. Unlike doping disorder, these tunable heterogeneities can probe competing order and intertwined phases in high-temperature superconductors, topological materials and vortex matter without affecting the underlying crystal-lattice constants.
The second program explores the fundamental aspects of out-of-equilibrium dynamics and self-assembly of bio-inspired materials for emerging applications. It investigates the structure and dynamics of active (actively consuming energy from the environment) self-assembled materials, such as colloids energized by external fields, suspensions of microswimmers, for the purpose of control, prediction, and design of novel out of equilibrium materials.
Current areas of research are:
Thermodynamic and electronic-transport studies of correlated electron systems as manifested in cuprates, iron-based superconductors, and in doped topological insulators. In particular, we use controlled particle irradiation to introduce heterogeneity to explore competing ground states, intertwined phases and robustness of superconductivity in these materials without affecting the underlying crystal-lattice structure. Areas and materials of interest include the nematic superconducting behavior in bulk topological superconductors (Cu, Sr, Nb)xBi2Se3, the competition of charge density waves and superconductivity in under-doped cuprates, and the co-existence of superconductivity and magnetism in iron based superconductor RbEuFe4As4.
Weyl and Dirac Semimetals
Angle-dependent magneto-transport and Fermiology studies of novel Weyl and Dirac semi-metals and their relationship of extreme magneto resistance (XMR) and negative magnetoresistance to topological features of the electronic band structure. Areas and materials of interest include in WTe2, (La, Y)Sb and NbP, among others.
Coupled Magnetic Spin-Textured and Superconducting Heterostructures
Exploration of novel magnetic spin ice structures and their coupling to superconductors, 2DEG systems and topological materials to develop novel strategies to control vortex dynamics, quantum Hall effect and Berry phases. Current studies are focused on tailoring vortex structure and motion via nano-magnetic artificial spin-ice related structures and patterned magnetic overlayers to realize magnetic pinning. These studies are coupled with molecular dynamics simulations to elucidate the dynamics of single and collective vortex motion.
Vortex Dynamics and Critical Current by Design
Development of efficient pinning landscapes via particle irradiation induced defects with various size, shape and distributions and the utilization of geometric vortex confinement effects in superconducting thin films and nanowires. These studies are coupled with large-scale time-dependent Ginzburg-Landau simulations to elucidate the dynamics of single and collective vortex motion and to establish quantitative description of different pinning regimes and its relationship to the enhancing the critical current.
Theoretical and experimental investigation of the collective behavior underlying high power THz radiation from synchronized Intrinsic Josephson Junctions in high temperature superconducting meso-crystals. The goal here is to enable THz-on-a-chip platform for novel high-speed electronics.
Dynamics of Active Self-Assembled Materials
The program focuses on the design of novel smart materials that can arise from a fundamental understanding of dynamic self-assembly and organization far from equilibrium. To obtain the deep insight into the problem at hand, and to extract parallel mapping rules among different active systems, we explore two highly complementary model systems: a synthetic system of active colloids energized by electric and magnetic fields and a bio-inspired system of a suspension of active swimmers in anisotropic fluids such as liquid crystals. The main difference between these systems is the way energy is injected: colloids are energized by an external applied electric or magnetic field whereas micro-swimmers are self-propelled. The program correlates the dynamics of both synthetic and live agents to develop understanding of the fundamental rules governing the emergence of self-assembly and organization away from equilibrium.