Manipulating Moirés by Controlling Heterostrain in van der Waals Devices

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Van der Waals (vdW) moirés create tunable superlattices with significant control over electronic properties.
• Current methods for moiré superlattice manipulation are limited.

Purpose of the Study:

• To demonstrate in situ manipulation of moiré superlattices using heterostrain control.
• To explore the effects of strain on moiré superlattice geometry and electronic properties.

Main Methods:

• Fabrication of a vdW device with graphene and hexagonal boron nitride (hBN).
• Application of uniaxial heterostrain exceeding 1% via a sliding technique.
• Transport measurements and electronic structure calculations.

Main Results:

• Successful modification of moiré superlattice shape and size through heterostrain.
• Observation of shifted resistance peaks and Landau fans in transport measurements, indicating an enlarged superlattice unit cell.
• Electronic structure calculations showing a shrunken and distorted moiré Brillouin zone, reduced bandwidth, and anisotropic Fermi surfaces.

Conclusions:

• Heterostrain control offers a powerful new method for tuning vdW moiré superlattices.
• This approach expands the accessible parameter space beyond traditional twist angle control.
• The ability to engineer moiré lattices with strain opens avenues for novel electronic device applications.