Investigation of magnetic dead layer formation at the interfaces of sputtered Ni80 Fe20 thin films

Abstract

In this thesis, magnetic dead layer formation at the interfaces of the sputtered Ni80Fe20 thin films has been investigated experimentally. Different insulators such as Ta2O5, Al2O3 and metallic Ta thin films have been deposited as seed and cap layers to determine the MDL formation at the interface of Ni80Fe20. The magnetization of samples has been probed by Vibrating sample magnetometry and X-ray reflectivity measurements have been carried out to investigate the thickness and roughness of the interlayers. Ta films cause the most MDL formation when grown as seed as well as cap layer. It has been observed that the thickness of MDL is strongly temperature dependent. MDL thickness decreases for all trilayers deposited except for Ta2O5/Ni80Fe20/Ta2O5 when they are exposed to 300 .C annealing temperature. Further annealing at 500 .C causes an interdiffusion between the layers and the thickness of the MDL increases. According to XRR measurements, the thickness of the inter alloy layers between the Ni80Fe20 and its adjacent layers is consistent with the thickness of magnetic dead layer calculated from Liebermann equation. MDL calculations reveal that SiO2/Ta/Ni80Fe20/Al2O3 multilayer has the lowest MDL thickness therefore might be a possible candidate to be used in spin valve structures.