# Investigation of Thermoelectric Properties in Altermagnet RuO2

## TL;DR

This paper explores the thermoelectric properties of altermagnet RuO2 and its potential in spintronic devices through a novel tunnel junction design.

## Contribution

The study introduces thermally induced magnetoresistance in RuO2-based junctions, leveraging its spin-polarized thermal transport.

## Key findings

- A RuO2/TiO2/RuO2 tunnel junction showed a maximum TIMR of 1756% at a 5 K temperature gradient.
- Spin-down and spin-up currents dominate in parallel and antiparallel structures, respectively.
- RuO2's thermoelectric efficiency suggests potential for waste heat recovery and spintronic applications.

## Abstract

An altermagnet, characterized by its distinctive magnetic properties, may hold potential applications in diverse fields such as magnetic materials, spintronics, data storage, and quantum computing. As a prototypical altermagnet, RuO2 exhibits spin polarization and demonstrates the advantageous characteristics of high electrical conductivity and low thermal conductivity. These exceptional properties endow it with considerable promise in the emerging field of thermal spintronics. We studied the electronic structure and thermoelectric properties of RuO2; the constructed RuO2/TiO2/RuO2 all-antiferromagnetic tunnel junction (AFMTJ) exhibited thermally induced magnetoresistance (TIMR), reaching a maximum TIMR of 1756% at a temperature gradient of 5 K. Compared with prior studies on RuO2-based antiferromagnetic tunnel junctions, the novelty of this work lies in the thermally induced magnetoresistance based on its superior thermoelectric properties. In parallel structures, the spin-down current dominates the transmission spectrum, whereas in antiparallel structures, the spin-up current governs the transmission spectrum, underscoring the spin-polarized thermal transport. In addition, thermoelectric efficiency emphasizes the potential of RuO2 to link antiferromagnetic robustness with ferromagnetic spin functionality. These findings promote the development of efficient spintronic devices and spin-based storage technology for waste heat recovery and emphasize the role of spin splitting in zero-magnetization systems.