Analyze the characteristics of magnetic properties changes in NiFe2O4 induced by trapping polar gas

Our experiments aimed to show that highly polarized Ni-Fe-O materials are affected by polar gases, which change their magnetic properties. Gas molecules adsorbed onto the material changed its magnetic properties due to weak electronic interactions between metal atoms on the interface and surrounding gas molecules. The coercivity and blocking temperature of the material were found to change in opposite directions for ozone was-20 oe and 10 K decrease and carbon monoxide was +40 oe and 20 K increased, owing to their distinct electron affinities. Density Functional Theory calculations supported our findings, revealing that gas adsorption alters the electric field and the spin-charge distribution, leading to a shift in the Fermi level and the movement of the top two layers of atoms due to electrostatic force. These shifts cause changes in the magnetic anisotropy. These changes were reversible upon desorbing the gas from the material's surface, which was facilitated by the molecular attraction between the gas and the material. Overall, our experimental and theoretical results provide a deeper understanding of the impact of polar gas interactions with magnetic material surfaces.

Automated summary

Our experiments demonstrated that highly polarized Ni-Fe-O materials can be influenced by polar gases, resulting in changes to their magnetic properties. Adsorbed gas molecules altered the material's magnetic properties through weak electronic interactions at the metal atom-gas molecule interface. Coercivity and blocking temperature of the material exhibited opposite changes for different gases due to variations in their electron affinities. Density Functional Theory calculations confirmed that gas adsorption induced alterations in the electric field and spin-charge distribution, leading to shifts in the Fermi level and movement of top atomic layers. These shifts ultimately affected the material's magnetic anisotropy. Importantly, these changes were reversible upon desorption of the gas, facilitated by molecular attraction between the gas and material. Overall, our experimental and theoretical findings enhance the understanding of polar gas interactions with magnetic material surfaces.