Abstract

This work explores the thermodynamic performance of a quantum Stirling heat engine implemented with an anisotropic spin-1 Heisenberg dimer as the working medium. Using the Hamiltonian of the system, the interplay of anisotropy, magnetic field, and exchange interactions and their influence is analyzed on the energy spectrum and the quantum level crossing. These results reveal that double-degenerate point (DDP) and a triple-degenerate point (TDP) play pivotal roles in shaping the operational regimes and efficiency of the quantum Stirling engine. At those points, the Carnot efficiency reaches higher work output and enhanced stability, making it a robust candidate for optimal thermodynamic performance. These findings highlight the potential of anisotropic spin systems as viable platforms for quantum heat engines and contribute to advancing the field of quantum thermodynamics. © 2025 Wiley-VCH GmbH.