Research

Topological crystalline insulators

TSS TCIWe are currently investigating new states of matter that arise in topological crystalline insulator due their unique valley degenerate topological properties. We can synthesize high mobility epilayers of PbSnSe to observe quantum coherent phenomena and quantum oscillations in magnetooptics and magnetotransport. Our goal is to study multivalley quantized Hall phenomena in these materials.

Magnetism in topological crystalline insulators

superlattice.jpgWe are studying two types of induced magnetism in topological crystalline insulators: bulk doping and proximity magnetism. We expect to reveal the intrinsic anomalous Hall effect resulting from the Berry phase of Dirac states in magnetic PbSnSe as well as a new phase of matter where the spin, valley and topological index are coupled. Magnetic topological crystalline superlattices can also be used to generate new quasiparticles such Weyl fermions and nodal line states.

(Bi,Sb)2Te3 by physical vapor deposition.

 

 

General audience digest on Quantum Materials

Why Quantum Materials?

We are on the brink of a technological revolution that will shift data processing and usage, from the individual scale to the ‘grid’ scale. Yes, with the advent of cloud storage and in-database processing, you’re going to start hearing experts talk about the ‘data grid’ much like infrastructure experts talk about our power grid.
datagrid slideSome of the major challenges that we are confronted with as scientists are the problems of lack of speed in processing and lack of energy efficiency in storage. More efficient materials are needed for devices that the grid relies on to process and store data.

Methods

Our method consists in a hybrid approach that combines material synthesis using MBE and CVD with electrical and optical characterization techniques. It allows us to produce, measure and identify materials with specific electronic and optical properties that can be integrated into functional devices. A list of the synthesis and characterization techniques used in our lab is given below:

  1. Molecular beam epitaxy (with the MBE group at Notre Dame)
  2. Chemical vapor deposition
  3. Infrared magnetooptical spectroscopy
  4. Magnetotransport
  5. Strong magnetic fields