Nonlinear Nernst effect in trilayer graphene at zero magnetic field

Area of Science:

• Condensed Matter Physics
• Materials Science
• Thermoelectrics

Background:

• The Nernst effect generates transverse voltage from temperature gradients, crucial for thermoelectric energy conversion.
• Linear Nernst effect is forbidden in non-magnetic materials due to time-reversal symmetry, but nonlinear effects are permitted.

Purpose of the Study:

• To experimentally observe and characterize the nonlinear Nernst effect (NNE) in non-magnetic ABA trilayer graphene.
• To investigate the potential of NNE for advanced thermoelectric applications.

Main Methods:

• Experimental observation of NNE using electric harmonic measurements.
• Application of an alternating temperature gradient at cryogenic temperatures (<12 K).
• Analysis of NNE dependence on temperature gradient and proximity to the charge neutrality point.

Main Results:

• Successful experimental detection of NNE in ABA trilayer graphene without an external magnetic field.
• NNE shows a quadratic dependence on the temperature gradient.
• A giant effective Nernst coefficient up to 300 µV K⁻¹ was measured at 2 K, surpassing linear coefficients in magnetic materials.
• A scaling law between NNE and the linear Seebeck effect was established, indicating skew scattering as the dominant mechanism.

Conclusions:

• The study demonstrates the feasibility of observing and utilizing NNE in non-magnetic materials.
• Findings suggest NNE as a promising mechanism for novel thermoelectric energy harvesting and cooling devices.
• This research provides a new pathway for developing advanced thermoelectric technologies.