Giant c-axis nonlinear anomalous Hall effect in T_d-MoTe₂ and WTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Physics

Background:

• The anomalous Hall effect typically breaks time-reversal symmetry due to internal magnetization.
• Non-centrosymmetric materials can exhibit a nonlinear anomalous Hall effect while preserving time-reversal symmetry.
• This nonlinear effect can originate from Berry curvature or asymmetric scattering.

Purpose of the Study:

• To report the observation of a significant nonlinear anomalous Hall effect in specific materials.
• To investigate the underlying mechanisms responsible for this effect in non-centrosymmetric compounds.
• To quantify the magnitude of the nonlinear anomalous Hall effect and related parameters.

Main Methods:

• Experimental investigation of the nonlinear anomalous Hall effect in the Td phase of MoTe2 and WTe2.
• Measurements conducted on non-centrosymmetric materials without intrinsic magnetic order.
• Analysis of temperature-dependent scattering mechanisms contributing to the observed effect.

Main Results:

• Observation of an extremely large c-axis nonlinear anomalous Hall effect in MoTe2 and WTe2.
• The effect is attributed to a combination of skew-scattering at higher temperatures and another low-temperature scattering process.
• A large Hall ratio (E⊥/E∥ = 2.47) and anomalous Hall conductivity (order of 8 × 10^7 S/m) were measured.

Conclusions:

• MoTe2 and WTe2 exhibit a substantial nonlinear anomalous Hall effect without magnetic order, driven by scattering.
• The findings highlight the role of non-centrosymmetry and scattering in generating large nonlinear Hall responses.
• This research opens avenues for exploring novel electronic phenomena and applications in topological materials.