Dual electronic states in thermoelectric cobalt oxide

TL;DR

This study reveals dual electronic states in thermoelectric cobalt oxide, showing how localized and itinerant electrons coexist and influence thermopower, offering insights for optimizing thermoelectric materials.

Contribution

It introduces the concept of dual electronic states in cobalt oxide, linking magnetic field dependence to spin-dependent transport and thermoelectric performance.

Findings

Negative magnetoresistance scaling indicates spin-dependent transport.

Dual electronic states explain coexistence of localized and itinerant electrons.

Results suggest new pathways to enhance thermoelectric efficiency.

Abstract

We investigate the low temperature magnetic field dependence of the resistivity in the thermoelectric misfit cobalt oxide [Bi1.7Ca2O4]0.59CoO2 from 60 K down to 3 K. The scaling of the negative magnetoresistance demonstrates a spin dependent transport mechanism due to a strong Hund's coupling. The inferred microscopic description implies dual electronic states which explain the coexistence between localized and itinerant electrons both contributing to the thermopower. By shedding a new light on the electronic states which lead to a high thermopower, this result likely provides a new potential way to optimize the thermoelectric properties.