Abstract
Enhancement in L10 transformation kinetics in FePt is achieved by incorporating an optimum concentration of ternary element Cu, which has limited solubility in the fcc FePt phase, into the FePt multilayer stack. Two different multilayer structures were deposited. In first multilayer Cu is deposited at one interface of Fe/Pt and in other Cu is alloyed with Fe and Pt layers by co-sputtering. One Fe42.5Pt42.5Cu15 alloy film is also prepared and detailed study of evolution of structural and magnetic properties as a function of isochronal annealing is done using XRD and Magneto Optic Kerr Effect (MOKE) measurements respectively. Annealing up to 200oC results only in intermixing in the multilayer structure, with no sign of L10 transformation. Annealing at 300oC for 1h results in partial transformation to L10 phase as evidenced by appearance of (001) superlattice peak as well as large increase in the coercivity. It is found that in the Fe(Cu)/Pt(Cu) multilayer exhibits significantly faster L10 transformation as compared to Fe/Pt/Cu multilayer or FePtCu alloy film. Inter-diffusion study using x-ray reflectivity measurements reveals that constant for interdiffusion in Fe(Cu)/Pt(Cu) is only marginally higher than that in Fe/Pt/Cu multilayer. The observed enhancement in L10 transformation rate in Fe(Cu)/Pt(Cu) multilayer is discussed in terms of possible enhancement of diffusivities of constituent species in fcc FePt phase.
Highlights
This paper was selected as FeaturedRaghavendra Reddy,[2] and Ajay Gupta1,a 1Amity Center for Spintronic Materials, Amity University UP, Sector 125, Noida 201 313, India 2UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001, India (Received 20 June 2018; accepted 17 September 2018; published online 16 October 2018)
Magnetic storage media has marketed a remarkable increase in the storage capacity of hard disk drives with a critical role of high anisotropic materials in advancing magnetic recording.[1,2] High magnetic anisotropy is crucial as the size reduction of a bit is constrained by the thermal instability of magnetization whereas high anisotropy ensures the thermal stability and makes the device suitable for high density recording media.[1]
At 300oC there are many changes evolving in x-ray diffraction (XRD) spectra which are summarized as follows, (i) satellite peaks completely attenuate, which is attributed to destruction in multilayer periodicity due to intermixing of Fe(Cu) and Pt(Cu) layers in M1 multilayer. (ii) secondly a strong superlattice peak emerges at 2θ=24o which is present only in alloy exhibiting some degree of order
Summary
Raghavendra Reddy,[2] and Ajay Gupta1,a 1Amity Center for Spintronic Materials, Amity University UP, Sector 125, Noida 201 313, India 2UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 001, India (Received 20 June 2018; accepted 17 September 2018; published online 16 October 2018)
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