Large coercive field in magnetic-field oriented ε-Fe2O3 nanorods

We report the fabrication and magnetic coercive field of oriented ε-Fe2O3 nanorods. Oriented ε-Fe2O3 nanorods embedded in SiO2 matrix were obtained by a sol–gel method under an applied external magnetic field. The longitudinal axis, which corresponds to a-axis of the crystal structure of ε-Fe2O3 nanorods, was oriented parallel to the direction of external magnetic field. The sample achieved a magnetic coercive field along the longitudinal axis of 23.4 kOe, which is the largest value among metal oxide-based magnetic materials. The shape of the magnetic hysteresis loop is well understood by considering the magnetization rotation process and the uniaxial magnetic anisotropy.