Maneuvering the magnetic anisotropy in single-phase nanocrystalline α-FeCo via external static magnetic field assisted one dimensional growth

Abstract

Magnetic anisotropy in magnetic nanostructures is highly desirable for the manufacturing of magnetic data storage devices. Therefore, in the present work, the effective magnetic anisotropy is investigated in α-FeCo nanoparticles (NPs) and nanowires (NWs) prepared using hydrazine reduction method. The growth of the NWs was manifested by applying external static magnetic field using bar magnets during synthesis which promoted the continuous growth up to 4 µm of average length and an average diameter of ~ 294 nm. The NP-formation as well as NW-growth adopted the phenomena of Ostwald ripening. The NWs demonstrated the enhanced saturation magnetization, enhanced effective magnetic anisotropy and reduced coercivity as compared to the corresponding NPs. The enhanced magnetic properties of the NWs have been associated with the magnetic force exerted by the external magnetic field during growth which aligned the crystallites along the direction of magnetic field together with the reorientation of the easy axis< 100 > of FeCo along the long axis of the wire. The assistance of the magnetic field during growth enhanced the ease of magnetization along the long axis of the wire. Additionally, the growth induced shape magnetic anisotropy via induced the dipolar interactions lead to the enhanced effective magnetic anisotropy. Thereby, it can be suggested that the external magnetic field applied during synthesis not only plays a primary role in the growth of NWs but also enhances the intrinsic magnetic properties of the material.