Research
Our lab is focused on three main topics:
Oxide interfaces
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Oxides often share the same crystal structure. Advanced thin film deposition technology allows us to grow one oxide on top of the other and create an artificial crystal. The interface between the two oxides can combine properties from the constituent materials. For example: ferroelectricity and ferromagnetism, superconductivity and ferroelectricity. Furthermore such interface can also be very different from its constituents. For example it can be conducting and even superconducting and/or magnetic despite the two non-magnetic and insulating parent compounds. The hallmark example is the interface between SrTiO3 and LaAlO3. Both are non-magnetic insulators but the interface is superconducting with interesting magnetic properties. In our laboratory we grow such interfaces and study the interplay between various orders such as: superconductivity and ferroelectricity, superconductivity and magnetism and topological superconductivity.
Unconventional superconductivity and superconductivity on the nano-scale
Aluminum grains (diameter~3nm). Magnification x709,000 (TEM image).
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Despite many years of research, unconventional superconductivity in many systems such as cuprates, iron-based pnictides, nickelates, and other materials still defies the solution. While the standard theory for superconductivity, the Bardeen-Cooper-Schrieffer (BCS) theory, can describe superconductivity in metals and alloys, unconventional superconductivity is still a matter of intense scientific research. We are studying new superconductors and older superconductors that are still awaiting a microscopic description. We use various probes such as tunneling spectroscopy, thermal and electrical transport, heat capacity, and optical studies.
Superconductivity is a macroscopic quantum phenomenon. In a superconductor, the number of charge carriers is not well defined, but the phase can be determined and controlled. However, when the superconducting specimen is constituted of weakly connected nano-grains, the opposite happens, and while the number of particles can be accurately determined, the phase strongly fluctuates. This results in many interesting physical phenomena. In our laboratory, we can probe superconducting fluctuations and their dependence on the nanostructure of the sample.
Topological
Materials
In a 3D topological insulator conducting surface-states are protected by time-reversal symmetry. While in 2D topological material, protected edge states lead to interesting transport phenomena. In our laboratory, we study the transport properties of these states and their tunneling and point contact spectra and implement topological materials in devices possibly useful for quantum computation.
