Impact of the CoFe microstructure etched surface oxidation on Co spin and orbital moment

Abstract

Patterned ferromagnetic thin film shows promising applications in ultra-high density magnetic storage, magnetoresistive transducer, magnetic random access memory and many other devices. Since the performance of these devices is closely associated with the magnetic properties of the etched patterns, it is necessary to study the effects of freshly etched surface oxidation on the magnetic properties of the patterned microstructures. In the current work, were carried out an X-ray Magnetic Circular Dichroism (XMCD) study on a 50 nm Co0.9Fe0.1 continuous thin film and a related patterned Co0.9Fe0.1 grating structure etched with a 2 μm period. Based on the sum rules, the spin and orbital moments were calculated for these two samples, respectively. The results indicated that the spin and orbital moments of grating structure (1.34µB and 0.24µB, respectively) decreased 17.3% compared with the corresponding continuous film (1.62µB and 0.29µB, respectively). We proposed that the moment decreasing of the patterned grating structure was mainly caused by the etched surface oxidation during the pattern manufacture process. The oxidation ratio of Co element in the patterned grating structure is 14.4% calculated from X-ray absorption spectroscopy (XAS) measurement. Considering the oxidation ratio, we amend the spin and orbital moment of Co and the amended result is basically in accordance with that of continuous film, demonstrating that the difference of the spin and orbital moments between the sub-micron grating unit and the continuous film is really caused by the oxidation.