Magnetic Properties of Ultrathin As-deposited and Annealed Ta/CoFeB/TaOx Heterostructures

Abstract

In order to meet the ever-increasing demand of magnetic recording industry, it is important to developferromagnetic thin film heterostructure compatible for magnetic memory device. Here, we have developed ultrathin ferromagnetic film of transition metal borides(CoFeB) which has huge potential to be integrated in magnetic memory devices. In particular, we have studied the surface roughness and magnetic properties of sputter deposited Substrate/1 nm Ta/1.5 nm CoFeB/1nm TaOx heterostructures. Magnetic properties investigation of as-deposited and 300 ⁰C annealed Ta/CoFeB/TaOx heterostructure using vibrating sample magnetometer indicates the presence of in-plane anisotropy in both the film stacks and a reasonable increase in the saturation magnetization of annealed film stack. Importantly, possible boron diffusion as well as partial crystallization of CoFeB layer due to annealing play crucial roles in governing the magnetic properties in these film stacks. These results provide in-depth insight into the factors affecting saturation magnetization of such ultrathin film heterostructures.