Detecting Lifshitz Transitions Using Nonlinear Conductivity in Bilayer Graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Second-order nonlinear electrical response (NLER) is a key property of materials lacking inversion symmetry.
• NLER offers insights into electronic band structures of atomically thin quantum materials.
• The effect of Lifshitz transitions on NLER in such systems was previously unexplored.

Purpose of the Study:

• To investigate the impact of Lifshitz transitions on the NLER in bilayer graphene (BLG).
• To establish NLER as a tool for probing electronic band structure changes in quantum materials.

Main Methods:

• Experimental investigation of NLER in bilayer graphene.
• Analysis of NLER sign changes near Lifshitz transitions at temperatures T ≥ 10 K.
• Characterization of NLER modulation by doping and interlayer potential.

Main Results:

• NLER exhibits a sign change near Lifshitz transitions in BLG, observable even at elevated temperatures (≥ 10 K).
• NLER at the band edge is influenced by extrinsic scattering and intrinsic Berry curvature dipole.
• Second-order conductivity in BLG reached over 30 µm V⁻¹ Ω⁻¹ at 3 K, a new record.

Conclusions:

• NLER is a sensitive probe for detecting Lifshitz transitions in quantum materials.
• External tuning of doping and interlayer potential allows control over NLER.
• This study highlights NLER's potential for characterizing complex electronic properties of 2D materials.