Reversible control of the magnetization of Fe3O4 via lithium ions

In this report, a reversible control of Fe3O4 saturated magnetization by Li ions is demonstrated. A miniature Li ion battery (LIB) was assembled using a Fe3O4 nanoparticle layer as the active cathode. A stable magnetism modulation is realized by a nondestructive electrochemical process in which the lithium insertion results in a valence change and partial redistribution of Fe cations in the crystal structure. The relation between the discharge voltage and the chemical phases were studied by ex situ X-ray diffraction and magnetic measurement. In a suitable discharge potential range, a reversible control of Fe3O4 saturated magnetization was obtained without structural damage to the magnetic electrode. The experimental results indicate by further optimizing the LIB's performance, a large reversible change in magnetization could be realized at room temperature, suggesting the potential for future practical applications.