High-Performance THz Sensing Based on Layered Topological Semimetals

The emergent atomically thin layered materials enable the unique control of new phases of matter for high-performance electronics and optoelectronics. One remarkable example is the recent discovered nonlinear Hall effect (NLHE) in topological semimetals, which is mediated by their diverging quantum geometrical properties [1-3]. In this talk, I will report how we leverage this new notion for high-performance THz optoelectronics. Firstly, I will review how the certain polar stacking order and corresponding quantum geometrical properties of layered topological semimetals can substantially influence their electron transport and memory switching [3]. Along this line, I will show our recent demonstration on high-performance THz sensing devices based on those new discovered effects [4]. In particular, we investigate the NLHE response in THz regime on a layered type-II Weyl semimetal in both noninteracting state and correlated state. Leveraging a custom-designed and in-house fabricated plasmonic photosensing device, we attained ultralarge and tunable photoresponsivity in this atomically thin topological semimetal. Moreover, the intrinsic response time is down to picosecond level. Our findings illuminate a new mechanism for low-energy photon harvesting and transduction via quantum properties. The results also pave the way towards a wide range of THz applications in communication and imaging based on layered topological semimetals.<br/><br/>References:<br/><br/>[1] Q. Ma et al., Observation of the nonlinear Hall effect under time-reversal-symmetric conditions, <i>Nature</i> 565, 337 (2019).<br/>[2] K. Kang et al., Nonlinear anomalous Hall effect in few-layer WTe₂, <i>Nature Materials</i> 18, 324 (2019).<br/>[3] J. Xiao et al., Berry curvature memory through electrically driven stacking transitions, <i>Nature Physics</i> 16, 1028 (2020).<br/>[4] T. Xi et al., High-performance THz sensing based on layered correlated topological semimetals, submitted (2024).