Recent research has unveiled significant superconductivity in a newly identified structure known as a supermoiré lattice, which consists of twisted trilayer graphene. This discovery, detailed in a paper published in Nature Physics on February 15, 2026, suggests promising avenues for the development of advanced quantum materials.
Researchers from the École Polytechnique Fédérale de Lausanne, Freie Universität Berlin, and other institutions conducted the study, which highlights how the arrangement of multiple graphene layers can drastically influence electron behavior. The supermoiré lattice features overlapping moiré patterns that arise from stacking two or more graphene layers at a slight twist angle, leading to complex electronic states, including superconductivity.
The study’s senior author, Mitali Banerjee, explained that the original intention was to create a device with two identical twist angles. However, through experimentation, the team, led by graduate student Zekang Zhou, discovered that varying the twist angles produced unexpected results and a distinctive phase diagram. Zhou’s measurements revealed that the system behaved differently when subjected to electric fields in opposite directions, leading to the emergence of resistive states in multiple areas of the material.
“This rich phase diagram inspired us to pursue this system,” said Banerjee. The research team aimed to investigate whether strong superconductivity could develop in a twisted trilayer graphene system that lacked mirror symmetry. They conducted low-temperature electrical transport measurements, tuning carrier density and displacement fields to map the phase diagram of their device.
One of the key indicators of superconductivity is a significant reduction in electrical resistance, often nearing zero. The researchers reported observing this near-zero resistance, suggesting the presence of superconducting states. They further validated their findings through temperature-dependent measurements, which indicated that the superconducting state was suppressed as temperatures rose. They also identified strong nonlinear transport behaviors, revealing a transition from superconductivity to a normal state at a critical direct current that was influenced by an out-of-plane magnetic field.
The experiments demonstrated that the superconducting states in the twisted trilayer graphene device were uniquely suppressed by magnetic fields. Despite the absence of mirror symmetry due to the differing twist angles, the device exhibited robust superconductivity. Banerjee noted that the presence of what they termed a supermoiré lattice was confirmed through the observation of Brown-Zak oscillations. These oscillations indicate that electrons are influenced by a larger periodic structure, further validating the formation of a supermoiré lattice.
The implications of this research extend beyond academic interest. Over the past decade, twisted graphene systems have gained attention for their potential to unveil diverse quantum phases. Banerjee indicated that the interference between distinct moiré lattices introduces a new degree of freedom, essential for exploring and realizing novel quantum states.
“Our findings demonstrate that in twisted multilayer systems, this degree of freedom broadens our understanding of quantum phases inherent to original moiré lattices,” said Banerjee. The outcomes of this study could soon guide the design of materials and devices with innovative electronic properties, which may be crucial for future quantum technologies.
The research team plans to continue their studies, focusing on systems where moiré quasicrystals coexist with supermoiré lattices. They aim to determine the specific conditions necessary to stabilize a supermoiré lattice within a multidimensional parameter space. Banerjee concluded, “We are also investigating the microscopic origins of superconductivity in our devised system, which exhibits behavior akin to twisted bilayer graphene combined with a monolayer graphene modulated by a supermoiré potential.”
This research contributes to a growing body of knowledge that could significantly impact the design of next-generation quantum devices and materials.
