Observations of Aharonov-Bohm Conductance Oscillations in CVD-Grown Graphene Rings at 4K

Abstract

We present the observations of Aharonov-Bohm (AB) oscillations in chemical vapor deposition (CVD)-grown graphene rings via magnetotransport measurements at 4K under out-of-plane external magnetic fields up to +/−2.1 T. Incorporating a baseline subtraction of the original conductance data allowed us to observe two-terminal conductance oscillations with a spacing of ΔB _AB of 3.66 to 32.9 mT from the ring with an inner radius of 200 nm and arm-width of 400 nm, and spacing of ΔB _AB from 2.1 mT to 8.2 mT from the ring with an inner radius of 400 nm and an arm-width of 400 nm. The fast-Fourier transform (FFT) data showed AB oscillation periods, with the interval of the h/e fundamental mode given by 30/T to 273/T for the ring with the inner radius of 200 nm and arm-width of 400 nm, and 122/T to 488/T for the ring with the inner radius of 400 nm. The broad spreading of FFT peaks is due to the aspect ratio of the inner radius r₁ and the width w of the ring, r/w ∼ 1. Systematic numerical simulations were performed to elucidate the relation between the AB oscillation frequency and the geometry of the ring. This work shows AB oscillations in CVD-grown graphene rings at an elevated temperature (4K).