Gate-tunable Veselago interference in a bipolar graphene microcavity

Xi Zhang; Wei Ren; Elliot Bell; Ziyan Zhu; Kan-Ting Tsai; Yujie Luo; Kenji Watanabe; Takashi Taniguchi; Efthimios Kaxiras; Mitchell Luskin; Ke Wang

doi:10.1038/s41467-022-34347-w

Gate-tunable Veselago interference in a bipolar graphene microcavity

Nat Commun. 2022 Nov 7;13(1):6711. doi: 10.1038/s41467-022-34347-w.

Authors

Xi Zhang^#¹, Wei Ren^#¹, Elliot Bell¹, Ziyan Zhu^{2

3}, Kan-Ting Tsai¹, Yujie Luo^{4

5}, Kenji Watanabe⁶, Takashi Taniguchi⁷, Efthimios Kaxiras^{2

8}, Mitchell Luskin⁹, Ke Wang¹⁰

Affiliations

¹ School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA.
² Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
³ Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
⁴ Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
⁵ Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, 55455, USA.
⁶ Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan.
⁷ International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki, Japan.
⁸ John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
⁹ School of Mathematics, University of Minnesota, Minneapolis, MN, 55455, USA.
¹⁰ School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, 55455, USA. kewang@umn.edu.

^# Contributed equally.

Abstract

The relativistic charge carriers in monolayer graphene can be manipulated in manners akin to conventional optics. Klein tunneling and Veselago lensing have been previously demonstrated in ballistic graphene pn-junction devices, but collimation and focusing efficiency remains relatively low, preventing realization of advanced quantum devices and controlled quantum interference. Here, we present a graphene microcavity defined by carefully-engineered local strain and electrostatic fields. Electrons are manipulated to form an interference path inside the cavity at zero magnetic field via consecutive Veselago refractions. The observation of unique Veselago interference peaks via transport measurement and their magnetic field dependence agrees with the theoretical expectation. We further utilize Veselago interference to demonstrate localization of uncollimated electrons and thus improvement in collimation efficiency. Our work sheds new light on relativistic single-particle physics and provide a new device concept toward next-generation quantum devices based on manipulation of ballistic electron trajectory.

Grants and funding

ARO MURI Grant No. W911NF14-0247/United States Department of Defense | United States Army | U.S. Army Research, Development and Engineering Command | Army Research Office (ARO)