Electron phase jumps in a graphene quantum Hall interferometer

We have developed a gate-defined graphene heterostructure to observe Fabry-Pérot interference of electrons propagating in quantum Hall edge channels [1]. Similar to recent experiments in GaAs quantum wells [2], the graphene heterostructure suppresses charging effects, revealing Aharonov-Bohm interference [1,3]. Moreover, the electron density in our graphene channel can be tuned electrostatically using local graphite gates. Here, we will discuss modulations of the Aharonov-Bohm phase appearing when multiple edge modes are present in the cavity. We observe periodic phase jumps in the Aharonov-Bohm oscillations of the interfering edge due to charge added to an adjacent mode. This observation is consistent with a new relation between the interference phase and the total electron charge contained in the interferometer [4]. The observation and proposed mechanism, arising from interaction between the spin-split Landau levels, may yield insight about anomalous reports of pairing and correlation between edge channels [5,6].



[1] Ronen, Y., Werkmeister, T. et al. Nat. Nano. 16, 563–569 (2021).

[2] Nakamura, J. et al. Nat. Phys. 16, 931–936 (2020).

[3] Déprez, C. et al. Nat. Nano. 16, 555–562 (2021).

[4] Feldman, D. E., Halperin, B. I. PRB 11 (2022).

[5] Choi, H. et al. Nat Commun. 6, 7435 (2015).

[6] Demir, A. et al. Phys. Rev. Lett. 126, 256802 (2021).