Our group performs nanoscale imaging and electronic device measurements to study the fundamental properties of quantum materials.
Nanoscale imaging with microwaves
We develop novel microwave imaging techniques for condensed matter physics, with the goal of visualizing and manipulating electronic states at ultra-low temperatures down to 50 mK. Our scanning microwave microscope quantifies the complex microwave response of a material, providing a local measurement of dissipation and screening in response to high frequency electromagnetic fields from the tip. By developing spatially-resolved and time-resolved measurement capabilities at frequencies across the GHz regime, we aim to shed new light onto topological edge states, Majorana modes, edge magnetoplasmons, domain wall conduction in new materials.
Topological states of matter
Topological solids can host electronic states that are protected from backscattering, manifested in conductance quantization that is remarkably independent of the shape or dimensions of the material. We employ scanning probe microscopy to visualize topological states in emerging quantum materials, including magnetic topological insulators, Dirac semimetals, and new candidates for the quantum spin Hall effect. We are also interested in development of methods to experimentally detect states governed by nonabelian statistics.
Quantum LEGOs: engineering new states of matter out of nanoscale building blocks
The remarkable electronic properties of graphene have sparked interest in layered heterostructures of 2D crystals and broader classes of low-dimensional quantum materials. Driven by advances in the assembly of heterostructures of 2D materials, our group focuses on engineering new functionalities by tuning the twist angle between neighboring sheets or combining materials with contrasting properties into hybrid structures. We seek to investigate new regimes where many body interactions, quantum confinement, the wavelike nature of electrons, or topology plays a dominant role.
Q. Zhang, T. Senaha, R. Zhang, C. Wu, L. Lyu, L. W. Cao, J. Tresback, A. Dai, K. Watanabe, T. Taniguchi, and M. T. Allen. Dynamic twisting and imaging of moiré crystals (2023).
M. T. Allen, O. Shtanko, I. C. Fulga, J. I.-J. Wang, D. Nurgaliev, K. Watanabe, T. Taniguchi, A. R. Akhmerov, P. Jarillo-Herrero, L. S. Levitov, A. Yacoby. Observation of electron coherence and Fabry-Perot standing waves at a graphene edge. Nano Letters (2017).