Detecting Lifshitz Transitions Using Nonlinear Conductivity in Bilayer Graphene

The second-order nonlinear electrical response (NLER) is an intrinsic property of inversion symmetry-broken systems that can provide deep insights into the electronic band structures of atomically thin quantum materials. However, the impact of Fermi surface reconstructions, also known as Lifshitz transitions, on the NLER has remained elusive. NLER is investigated in bilayer graphene (BLG), where the low-energy bands undergo Lifshitz transitions. Here, NLER undergoes a sign change near the Lifshitz transitions even at elevated temperatures T ≥ 10 K. At the band edge, NLER in BLG is modulated by both extrinsic scattering and interfacial-strain-induced intrinsic Berry curvature dipole, both of which can be finely tuned externally by varying doping and interlayer potential. Away from the band edge, BLG exhibits second-order conductivity exceeding 30 µm V^-1 Ω^-1 at 3 K, higher than any previous report. This work establishes NLER as a reliable tool to probe Lifshitz transitions in quantum materials.