Quantum spin-liquids are strongly correlated phases of matter displaying a highly entangled ground state. The strongly correlated nature of twisted Van der Waals materials offers them a versatile platform to study quantum spin-liquid physics. Yet, due to the unconventional nature of quantum spin-liquid states, finding experimental signatures of these states has proven to be a remarkable challenge. Here we show that magnetic S=1/2 impurities create resonant spinon zero modes in Dirac quantum spin-liquids at zero energy. We show that the emergence of such zero modes is associated with the low energy Dirac nature of the spinon excitations, and we explore the interference effects between different impurity states. Finally, we show that the spinon zero modes result in a zero frequency divergence in the spin structure factor, which can be probed by means of scanning tunnel spectroscopy and electrically-driven paramagnetic resonance. Our results highlight the dramatic effect of impurities in a Dirac quantum spin-liquid, providing a stepping stone towards identifying Dirac quantum spin-liquids through local real space measurement with scanning probe techniques.

Guangze Chen

Aalto University, Finland