Transverse response from anisotropic Fermi surfaces

Area of Science:

• Condensed Matter Physics
• Solid State Physics
• Materials Science

Background:

• Electron transport phenomena often rely on magnetic fields or topological properties like Berry curvature.
• Anisotropic bandstructures and Fermi surfaces are crucial for understanding electronic properties in many materials.

Purpose of the Study:

• To demonstrate that anisotropic and rotated Fermi surfaces can generate transverse electrical responses without external magnetic fields.
• To explore the role of broken $k_y \to -k_y$ symmetry in generating transverse conductivity.
• To establish a symmetry-based method for engineering transverse signals in low-symmetry materials.

Main Methods:

• Utilizing a two-dimensional continuum model to analyze bandstructure symmetry.
• Constructing a lattice model with tailored hopping parameters to replicate continuum dispersion.
• Employing a multiterminal geometry and the Büttiker-probe method for experimental simulation.

Main Results:

• A finite transverse conductivity arises from broken $k_y \to -k_y$ symmetry in anisotropic bandstructures.
• The transverse voltage directly corresponds to the predicted transverse response and scales with anisotropy.
• The effect diminishes when mirror symmetry is restored, unlike quantized responses in the quantum Hall effect.

Conclusions:

• Anisotropic Fermi surfaces offer a novel route to generate transverse electrical signals.
• This phenomenon provides a non-magnetic, non-topological mechanism for transverse response engineering.
• The findings open possibilities for designing new electronic devices based on material symmetry properties.