Abstract:

Topological materials contain robust electronic states against perturbation, leading to exotic fundamental properties and promising applications such as dissipationless electronics and fault-tolerant quantum computations. For a particular type of topological material, the Weyl semimetal (WSM), topology is manifested as a pair of topological singularities like momentum-space magnetic monopoles. In this seminar I will introduce our recent research on these paired singularities in a WSM. In one example, we show that how the topological singularities enable the visualization of electronic topology through ionic degrees of freedom called Kohn anomaly [1], while in another example, we show that how the singularities can be used to break the barrier of thermoelectric power factor by order-of-magnitudes [2]. We conclude by showing a broader phenomena and applications enabled by the topological singularity in a WSM.  

The references come with it: 

[1] T Nguyen, F Han, N Andrejevic, R Pablo-Pedro et al, Phys. Rev. Lett. 124, 236401 (2020)

[2] F Han, N Andrejevic, T Nguyen, V Kozii et al, arXiv:1904.03179. 

Bio:

Mingda Li is the Norman C. Rasmussen Assistant Professor at MIT Nuclear Science and Engineering Department. He completed his B.S in Engineering Physics from Tsinghua University in 2009, PhD in Nuclear Science and Engineering from MIT in 2015, and did his postdoc at MechE, advised by Prof. Gang Chen and late Prof. Millie Dresselhaus. His research focuses on using x-ray and neutron scattering probes to study topological quantum materials, and augment scattering spectroscopic analysis with machine learning.  

Zoom info: 

https://mit.zoom.us/w/98102489546