Caloric Phenomena and Stirling-Cycle Performance in Heisenberg- Kitaev Magnon Systems

TL;DR

This study explores how exchange anisotropy in Heisenberg-Kitaev magnon systems affects Stirling-cycle efficiency, revealing that Kitaev interactions enable higher efficiencies and tunability for nanoscale energy conversion.

Contribution

It demonstrates that Kitaev exchange asymmetry enhances caloric effects and efficiency in magnonic Stirling cycles, offering a new route for energy conversion in anisotropic magnets.

Findings

Kitaev interactions enable higher caloric effects than Dzyaloshinskii--Moriya interactions.

Spectral symmetry is preserved by DM interactions, leading to symmetric caloric responses.

Kitaev-driven cycles approach high efficiency saturation at negative couplings.

Abstract

We investigate the Stirling-cycle performance of a Heisenberg--Kitaev magnonic medium with Dzyaloshinskii--Moriya (DM) interactions. Using linear spin-wave theory, we show the DM interaction preserves spectral symmetry, yielding even caloric responses and symmetric Stirling engine efficiency. In contrast, bond-dependent Kitaev exchange asymmetrically distorts the magnonic density of states, enabling distinct direct and inverse caloric effects. Consequently, Kitaev-driven cycles achieve significantly higher efficiencies than DM-driven protocols, approaching a high-performance saturation regime for negative couplings. This establishes exchange-anisotropic magnets as highly tunable platforms for nanoscale solid-state energy conversion.