Cryogenic shock exfoliation for ultrahigh mobility rhombohedral graphite nanoelectronics

TL;DR

This paper introduces a cryogenic shock exfoliation method to produce large-area rhombohedral graphene flakes, enabling high-quality nanoelectronic devices with ultrahigh mobility and uniform magnetic properties.

Contribution

The authors develop a novel cryogenic shock exfoliation technique combined with low-pressure assembly to produce large, high-quality rhombohedral graphene flakes with high yield and uniformity.

Findings

Devices exceed 1300 μm² with 90% fabrication yield.

Uniform spin magnetism observed over 10x10 μm² area.

Disorder mean free path exceeds 200 μm at low temperatures.

Abstract

Rhombohedral multilayer graphene (RMG) offers a highly tunable platform for correlated electron physics, featuring field-effect control of magnetic, superconducting, and topological phases[1-24]. The promise of these materials has been held back by the limited abundance of rhombohedral stacking in natural graphite, which constrains both sample yield and useful area. Here we introduce 'cryogenic shock exfoliation' to produce large area rhombohedral graphene flakes which, combined with a low-pressure van der Waals assembly technique that preserves stacking order, enable highly uniform devices exceeding 1300 $\mu m^2$ with fabrication yields of 90%. Using scanning nanoSQUID-on-tip imaging, we demonstrate uniform spin magnetism over the full central 10 times 10 $\mu m^2$ area of our devices. Transverse magnetic focusing reveals a disorder mean free path exceeding 200 $\mu m$ at low temperatures. Within the flat surface bands of RMG[20], we observe a size-driven crossover from Poiseuille to porous electron flow in the intermediate-temperature regime of strong electron-electron hydrodynamics[16, 25], providing a further signature of ultrahigh device quality. Our approach overcomes a key materials bottleneck in the fabrication of mesoscopic rhombohedral graphene devices, paving the way for incorporating strongly correlated phases into two-dimensional nanoelectronics.