Simultaneous control of electrical and magnetic properties of LaFeO3-δ nanoparticles by contact of ethanol gas.

LaFeO 3-δ nanoparticles were prepared by citric sol-gel method, which show weak ferromagnetic (FM) behavior at room temperature with magnetization of 0.11 emu/g at 10 kOe. XPS indicates that La is rich at the surface region and Fe ions are in the mixed state of Fe 3+ and Fe 4+ . The double exchange interaction of Fe 3+ -O 2− -Fe 4+ between neighboring Fe 3+ and Fe 4+ ions would result in strengthened FM shell and weakened AFM core, which contribute to the observed FM behavior. The electrical and magnetic properties are coupled by the formation of Fe 4+ ions, which are mainly caused by oxygen adsorption at the surface region and by electrical valence compensation inside the core. Simultaneous control of electric resistance and magnetization has been achieved by contact of ethanol, which could react with the adsorbed oxygen at the surface region, leading to increased resistance and reduced magnetization. [ABSTRACT FROM AUTHOR]