Ultra-sensitive Optical Magnetometry and Magnetic Imaging

Our lab specializes in ultra-sensitive magneto-optical measurement and imaging using a unique instrument called loopless fiber-optical Sagnac interferometer microscope, which is developed from a loopless Sagnac interferometer technology that the PI co-invented during Ph.D. a decade ago (Physics Today "Search & discovery: Superconductor forms domains that break time-reversal symmetry", 2006). This is by far the most sensitive magneto-optical Kerr microscope in the world, and we use this unique instrument to study a wide range of materials from unconventional superconductors to vdW atomic layers to magnetic nano-structures. We have for the first time realized magnetic order in van der Waals atomic layers (Physics Today “Search and Discovery: Ferromagnetism found in two-dimensional materials”, Nature "Magnetism in flatland", 2017) that would open the door for atomic-sized spintronic devices. We are also pursuing ultra-sensitive medical magnetic imaging, which is on its way to achieving magnetic field sensitivity comparable to SQUID magnetometer. One of the major motivation is for room temperature functional brain imaging.

Topological Materials for Quantum Computers

We also specialize in sensitive electrical, thermal and mechanical measurements often at low temperature (mK) and high magnetic field (12 T). We are interested in the fabrication and investigation of quantum materials for constructing quantum computers and other novel electronic devices. These materials include topological insulators, atomic-thin oxide heterostructure, unconventional superconductors and v = 5/2 fractional quantum Hall state. In the past few years, our group has pioneered the study of topological Kondo insulator SmB6 (Nature “Hopes surface for exotic insulator”, 2012), and we have made perhaps one of the first working electronics devices based on SmB6: a micro RF oscillator device.