Researchers grow rhombohedral graphene at scale, opening a path to graphene-based quantum chips

Most graphite and graphene research has focused on conventional AB-stacked layers, in which each layer sits in a staggered, alternating pattern relative to the one below. Rhombohedral, or ABC-stacked, graphene instead shifts every layer in the same direction, with each three-layer sequence repeating – a subtle structural difference that gives rise to superconductivity and the quantum anomalous Hall effect, making it an attractive platform for topological qubits that are inherently resistant to noise. The catch is that rhombohedral stacking is thermodynamically unstable and rare in nature: in the lab, ABC-stacked graphene tends to spontaneously revert to the far more common AB form, and until now the only way to obtain usable flakes was to mechanically exfoliate graphite and search under a microscope for the small fraction – under 1% of samples – that happened to have the right stacking.

Researchers at Peking University, led by Liu Kaihui, together with Suzhou Laboratory, ShanghaiTech University, Wuhan University and the Chinese Academy of Sciences’ Institute of Physics, have developed a way to grow rhombohedral-stacked graphene with high purity and at sizes far beyond what was previously achievable, addressing a longstanding obstacle to using the material in quantum computing hardware.Most graphite and graphene research has focused on conventional AB-stacked layers, in which each layer sits in a staggered, alternating pattern relative to the one below. Rhombohedral, or ABC-stacked, graphene instead shifts every layer in the same direction, with each three-layer sequence repeating – a subtle structural difference that gives rise to superconductivity and the quantum anomalous Hall effect, making it an attractive platform for topological qubits that are inherently resistant to noise. The catch is that rhombohedral stacking is thermodynamically unstable and rare in nature: in the lab, ABC-stacked graphene tends to spontaneously revert to the far more common AB form, and until now the only way to obtain usable flakes was to mechanically exfoliate graphite and search under a microscope for the small fraction – under 1% of samples – that happened to have the right stacking.

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