Extremely low coercivity in Fe₃O₄ thin film grown on Mg₂TiO₄ (001)

摘要

We report very different magnetic properties of 40 nm-thick Fe3O4 thin films grown on tailored spinel substrate Mg2TiO4 (001) and on general substrate MgO (001). The sample on Mg2TiO4 (001) shows a very sharp Verwey transition with narrow hysteresis of only 0.5 K and a high transition temperature up to 126 K and, in particular, an extremely small coercivity as low as around 7 Oe from the Verwey transition to room temperature. This low coercivity is close to that of the single crystal bulk but several times smaller than that of the sample on MgO (001). Our work gives a first example of the magnetic properties in Fe3O4 thin film having higher Verwey transition than that of the single crystal bulk, which not only greatly expands our understanding about Fe3O4 but also provides a very good candidate for spintronic applications with quite low energy consumption.