Ph.D., 1998 - Brown University
Condensed matter physics studies properties of vast numbers of interacting electrons in solids. As a result of the interactions, materials exhibit emergent collective properties: the behavior of a 1mm sample when probed in experiment is very different from the response of individual atoms that make up the material. The collective properties are a consequence of order: in simple solids it is the arrangement of atoms in a regular crystal lattice that gives rise to its rigidity and also determines whether the material is a metal or an insulator. A plethora of different, and often more exotic, orders occurs in more complicated systems: from magnetic and charge to superconductivity and the "hidden" order.
The challenge of condensed matter physics is to understand how this fantastic complexity of behavior arises from basic quantum mechanics governing the motion of electrons, and to find an effective way to understand and describe the emergent properties. Theoretical approaches combine statistical physics (there are ~1023 electrons per cubic centimeter in a typical solid), quantum mechanics (electrons are fermions, which means that they avoid each other when filling up energy levels, and at or below room temperature they behave as quantum-mechanical particles), and treatments of strong interactions of many particles.
In my research I analyze the consequences of unusual orders on the experimentally measured quantities, use the experimental data to draw conclusions about the origin of the unconventional properties of strongly interacting electron systems, and investigate theoretical models for emergence of different types of exotic orders, their competition and coexistence. I am especially interested in the unconventional superconductivity in high-temperature copper oxide superconductors and heavy fermion materials and interplay of superconductivity and itinerant magnetism in these systems. I am also investigating the properties of materials near the Quantum Critical Points: points where a phase transition between two different ground states occurs at T=0 and and is accompanied by quantum mechanical fluctuations.