Low-symmetry materials unlock rich Berry curvature physics and anomalous transport phenomena that are forbidden in high-symmetry quantum systems through rigorous crystalline symmetry constraints. Current approaches rely on external fields or complex heterogeneous stacking to break crystalline symmetries, which hinders scalable device integration. In this work, we demonstrate surface premelting engineering to create wafer-scale low-symmetry graphene on germanium-110 [Ge(110)]. Controlled premelting forms striped germanium surface patterns that reduce graphene symmetry from D6h to C1v, producing a room-temperature nonlinear Hall conductivity of ~11 micrometers per volt per ohm. First-principles calculations attribute this to originating from overtilted massive Dirac cones of hybridized germanium bands and the graphene Dirac cone. Integrated nonlinear Hall rectifiers generate >20 millivolts of output from radio frequency input and drive commercial voltage boosters and light-emitting diodes, establishing a complementary metal-oxide semiconductor–compatible route toward wafer-scale nonlinear quantum devices.

The electronic properties of quantum materials are governed by crystalline symmetries through rigorous selection rules that dictate the allowed physical phenomena. In highly symmetric crystals, these constraints eliminate intrinsic anomalous transport through exact cancellation mechanisms, whereas low-symmetry materials systematically break these constraints to unlock rich Berry curvature physics and enable previously forbidden quantum geometric responses. For instance, twisted bilayer graphene aligned with hexagonal boron nitride reduces the point group from D6h to C1v, breaking inversion symmetry and activating Berry curvature–driven anomalous transport phenomena that are strictly forbidden in pristine graphene.

Current approaches to low-symmetry systems primarily rely on external field manipulation and complex heterogeneous stacking to break crystalline symmetries. The twisted graphene and two-dimensional (2D) transition metal dichalcogenide (TMD) moiré superlattices, for example, require strain engineering or perpendicular electric fields to break both inversion and C3 rotational symmetries to observe intrinsic nonlinear Hall effects (NLHEs). The fabrication of such heterostructures typically requires complex transfer processes that introduce structural defects and interface contamination, substantially reducing device reproducibility. Moreover, the requirement for additional external fields complicates on-chip system integration and increases the complexity of practical device architectures. Alternatively, intrinsic structural approaches exploit the inherent crystal structure symmetry of materials to achieve permanent symmetry reduction without external stimuli. For instance, quasi-1D moiré superlattices, such as nanotubes or nanoscrolls, have been reported in which the C3 rotational symmetry is broken, thus generating strong anisotropic responses with short-circuit current densities that are orders of magnitude larger than those in bulk materials. However, it is rather challenging to assemble these 1D materials into uniform arrays across macroscopic scales for large-area applications. Therefore, the synthesis of wafer-scale uniform low-symmetry moiré superlattices becomes essential for the realization of NLHEs in practical applications.

In this work, we develop surface premelting engineering (SPE) to create wafer-scale, low-symmetry graphene moiré superlattices with intrinsic Berry curvature–driven anomalous transport. By precisely controlling Ge(110) surface premelting and subsequent cooling during the growth of a single-crystalline graphene overlayer, we sculpt striped patterns on the top surface of Ge(110) that reduce the symmetry of the graphene overlayer from D6h to C1v. This symmetry reduction enables an unprecedented nonlinear Hall conductivity of χyxx ~ 11 μm V−1 ohm−1 at room temperature, which exceeds those of all state-of-the-art moiré or bulk materials systems. Scaling analysis and first-principles calculations reveal that this response originates from overtilted band anticrossings, where Ge-derived parabolic bands intersect the graphene Dirac cone 23.2 meV above the Fermi level. Strong interlayer hybridization opens tiny gaps at these crossings, creating overtilted massive Dirac cones—quasiparticles whose group velocity exceeds the Dirac velocity—that host divergent Berry curvature hotspots. Exploiting this exceptional χyxx, we demonstrate nonlinear Hall rectifiers (NRs) that generate stable dc voltages from 2.4-GHz Wi-Fi signals without external power. Because NR arrays can be fabricated on wafer-scale low-symmetry graphene/Ge(110) moiré superlattices, with the back-end-of-line (BEOL) processes, self-contained rectenna dies consisting of 3×3, 4×4, or 5×5 NR arrays can be built as well. For instance, a 4×4 NR array is able to generate more than 20 mV of dc output at −16 dBm of input power, which is sufficient to drive commercial voltage boosters and power light-emitting diodes (LEDs) under ambient conditions. Our study establishes a general and versatile platform for engineering diverse symmetry-broken moiré materials and opens an avenue toward design and scalable manufacturing of quantum devices.