Thermoelectric Effect at Quantum Limit in Two-Dimensional Organic Dirac Fermion System with Zeeman Splitting

TL;DR

This paper investigates the thermoelectric effect in a 2D Dirac fermion system with Zeeman splitting, revealing a broad local maximum in thermopower at high magnetic fields, contrasting with 3D systems.

Contribution

It provides experimental insights into thermopower behavior in 2D Dirac fermion systems with Zeeman splitting, highlighting differences from 3D Dirac/Weyl semimetals.

Findings

Broad local maximum of thermopower observed at high magnetic fields.

Zeeman splitting suppresses the predicted unbounded thermopower increase.

High-performance thermopower is challenging in 2D Dirac systems under strong magnetic fields.

Abstract

The thermoelectric effect in a two-dimensional (2D) massless Dirac fermion (DF) system at the quantum limit is discussed to verify the prediction of high-performance thermopower in an organic conductor \alpha-(BEDT-TTF)2I3. Because of relatively large Zeeman splitting in \alpha-(BEDT-TTF)2I3, the boundless increase of thermopower at high magnetic fields, predicted without the Zeeman effect, is hardly expected, whereas there appears to be a broad local maximum. This is characteristic of 2D DF systems with Zeeman splitting and is recognized in the previous experiment. In contrast to 3D Dirac/Weyl semimetals with robust gapless features, it might be difficult to realize high-performance thermopower in real 2D DF systems under high magnetic fields.