▎ 摘　　要

Magic-angle twisted bilayer graphene (tBLG) displays a variety of symmetry-broken phases, correlated Chern insulators, orbital magnetism and superconductivity(1-8). In particular, the anomalous Hall effect has been observed when the bands are filled with an odd number of electrons per moire unit cells(5,6,9), indicating the emergence of a zero-field orbital magnetic state with spontaneously broken time-reversal symmetry(10-12). Here we present measurements of two tBLG devices with twist angles slightly away from the magic angle and report the observation of the anomalous Hall effect at half filling of both the electron and hole moire bands. We suggest that two factors-the increased band dispersion away from the magic angle, and substrate potentials from the encapsulating boron nitride-probably play critical roles in stabilizing a valley-polarized ground state at half filling. Our findings further expand the rich correlated phase diagram of tBLG, and indicate the need to develop a more complete understanding of its manifold of closely competing symmetry-breaking orders.