Strain-Induced Magnetic and Electronic Transitions in 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.