Title: Valley engineering in two-dimensional semiconductor devices

Speaker: Xiaomu Wang (Nanjing University)

Time&Location: 12:00 pm, Mar. 21,  Room B501, Tangzhongying Building 

Abstract: Valleys, the extremum points in the band dispersion relationship, can be used as a new degree of freedom to carry information.Based on thevalley pseudo-spin degrees of freedom, Valleytronicsis an emerging technology in post-Moore's law semiconductor development, promising to solve the bottleneck encountered in scaling down the advanced CMOS processes.In particular, two-dimensional materials with broken inversion symmetry have two energy valleys with contrary Berry curvatures, which are degenerate but inequivalent at the edge of the Brillouin zone and can be directly controlled by the electric field, whichmakes them particularly suitable for building quantum devices.This report introduces the recent progress in the field of valleytronics by our group. First, we will discuss the valley Hall effect, chiral nano-antennas, elementary excitation energy valley polarization,and other technologies.Then, we will demonstrate solid-state transistor devices and all Stokes-integrated polarization devices, which can achieve the complete set of functions for generating, transmitting, detecting, and controlling valley information at room temperature.Finally, we will discuss the application of related Berry curvature polarization methods in exploring the topological properties of strongly correlated quantum materials.

Biography:  Xiaomu Wang, a professor at the School of Electronic Science and Engineering at Nanjing University. He mainly focuses on the research of low-dimensional semiconductor optoelectronic devices and device physics. He received his Ph.D. from the Chinese University of Hong Kong in 2012 and subsequently conducted postdoctoral research at the University of Cambridge and Yale University. He was selected for the Overseas High-Level Talents Youth Program and joined Nanjing University in 2016.