Strain-Induced Magnetic and Electronic Transitionsin Prussian Blue Analogues: A First-Principles Study

Prussian blue analogues (PBAs) have gained significant attention for their potential applications in K-ion batteries due to their stable octahedral coordination structure, high ionic conductivity, and ability to reversibly intercalate potassium ions, making them promising candidates for efficient energy storage solutions. We employed density functional theory calculations to investigate the electronic and magnetic properties of K₂Co[Fe(CN)₆] under various strains and substitutions. Our study focuses on the Jahn–Teller distortion and spin transitions between high-spin and low-spin states in different structural phases, including cubic, tetragonal, and monoclinic forms. We find that the tetragonal structure exhibits greater stability compared to the cubic phase, with potential evidence for a monoclinic phase. By applying isotropic and uniaxial strains, we analyze the changes in the magnetic moments, density of states, and stress–strain relationships, revealing a strain-induced transition from half-metallic to semiconducting behavior. These findings contribute to a deeper understanding of the strain-dependent properties of PBAs, offering insights into their practical applications in spintronics and energy-storage devices.