Microscopic Understanding of Negative Magnetization in Cu, Mn, and Fe Based Prussian Blue Analogues

A crossover of the field-cooled magnetization from positive to negative has been observed below the magnetic ordering temperature (17.9 K) in a multimetal Prussian Blue analogue (PBA), Cu_0.73Mn_0.77[Fe(CN)₆]·zH₂O. The reverse Monte Carlo (RMC) modeling (using the program RMCPOW) has been used to derive the various scattering contributions (e.g., nuclear diffuse, nuclear Bragg, magnetic diffuse, and magnetic Bragg) from the observed neutron diffraction patterns. The RMC analysis combined with the Rietveld refinement technique show an antiferromagnetic ordering of Mn moments with respect to the Cu as well as the Fe moments. Our study gives the first neutron magnetic structure evidence towards the microscopic understanding of the negative magnetization in the PBAs. This information can be effectively utilized to design suitable PBAs for making multifunctional devices.