Materials Science Research Lecture

Abstract:

Low-dimensional materials offer a rich playground for exploring and, in some cases, tuning superconducting states, including states with non-trivial topologies or with effective bandstructures of higher-order dimensionality than in bulk materials. These intriguing properties often arise from broken symmetries, which can be either intrinsic to the material in its 2D limit or obtained by further nanostructuring into devices with specific geometries. This talk will focus on two main examples. In the first example, I will discuss a surprising two-fold anisotropy of the superconducting state of few-layer NbSe2, which is absent in the normal state. The experimental results suggest a possible competition between the conventional s-wave pairing instability characteristic of the bulk and a competing d- or p-wave instability that emerges in the few-layer limit. In the second example, I will discuss semiconductor-superconductor hybrid quantum wells as a playground for creating new electrostatically-tunable Josephson effects and Andreev bandstructures. Devices made from such hybrid structures realize a full platform on which to search for topological Weyl nodes or engineer tunable effective bandstructures in more than three dimensions. Related devices also enable observation of a highly-tunable non-reciprocal Josephson effect, i.e. a superconducting diode.

More about the Speaker:

Vlad Pribiag is Associate Professor of Physics at the University of Minnesota. He received his PhD from Cornell University and, prior to starting at Minnesota, was a VENI postdoctoral scholar in the quantum transport group at the Kavli institute Delft. His research focuses on experimental investigations of one- and two-dimensional quantum devices and materials, with a focus on possible applications to future quantum-enabled computing technologies. He was awarded the International Union of Pure and Applied Physicists Young Investigator Prize in Low-Temperature Physics in 2017 for his investigations of "superconductivity in the edge modes of two-dimensional topological insulators [and] spin-dependent quantum transport in one-dimensional semiconductors with strong spin-orbit coupling." He received an Alfred P. Sloan Fellowship (2017), and a University of Minnesota McKnight Land-Grant Professorship (2019), the University's leading award for junior faculty.