Fingerprints of Composite Fermion Lambda Levels in Scanning Tunneling Microscopy

Composite fermion (CF) is a topological quasiparticle that emerges
from a non-perturbative attachment of vortices to electrons in
strongly correlated two-dimensional materials. Similar to
non-interacting fermions that form Landau levels in a magnetic field,
CFs can fill analogous ``Lambda'' levels, giving rise to the
fractional quantum Hall (FQH) effect of electrons. Here, we show that
Lambda levels can be directly visualized through the characteristic
peak structure in the signal obtained via spectroscopy with the
scanning tunneling microscopy (STM) on a FQH state. Complementary to
transport, which probes low-energy properties of CFs, we show that
high-energy features in STM spectra can be interpreted in terms of
Lambda levels. We numerically demonstrate that STM spectra can be
accurately modeled using Jain's CF theory. Our results show that STM
provides a powerful tool for revealing the anatomy of FQH states and
identifying physics beyond the non-interacting CF paradigm.


Songyang Pu, Ajit C. Balram, Yuwen Hu, Yen-Chen Tsui, Minhao He,
Nicolas Regnault, Michael P. Zaletel, Ali Yazdani, Zlatko Papić,
arXiv:2312.06779