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This article reports on the Ar+ ion irradiation induced modifications of Co/Alq 3 /Si-substrate bilayer thin film. Irradiation was carried out with 10 keV Ar+ ions at a fluence of 1 × 1016 ions/cm2. To study structural and magnetic modifications, x-ray reflectivity (XRR) and magneto-optical Kerr effect (MOKE) techniques, respectively have been utilized. XRR analysis reveals a significant reduction of electron density of the Co layer and enhancement of intermixing of Co and Alq 3 at the Co/Alq 3 interface after ion irradiation. MOKE measurements affirm that saturation magnetization reduces by a factor of about 3 due to irradiation without any detectable changes in the coercivity. XRR analysis and Monte Carlo simulation demonstrate the ion irradiation induced defects formation due to Ar implantation and enhancement of interface mixing between Co and Alq 3 is the main cause of the reduction in saturation magnetization. [ABSTRACT FROM AUTHOR]

• 10 keV Ar+ ion implantation induced modifications has been explored in Co 20 Fe 60 B 20 /SmCo 5 bilayers. • Magnetic Coercivity has been increased by more than ten times after implantation. • X-ray reflectivity study revealed ion implantation causes significant microstructural modifications. • Enhancement of coercivity attributed to mixing of elements at the interface and Ar implantation induced defects creation. 10 keV Ar+ ion implantation induced modifications of nanoscale Co 20 Fe 60 B 20 /SmCo 5 /Si-substrate heterostructures have been investigated. Magneto-optic Kerr effect study reveals that the coercivity enhances by more than ten times after implantation. Implantation gives rise to an increase in surface roughness and densely packed grains as evident from the Atomic Force Microscopy study. X-ray reflectivity analysis manifests ion beam induced intermixing between elements of two layers at the interface and significant changes in the internal structure. Monte Carlo simulation study corroborates the x-ray reflectivity results. Enhancement of coercivity attributed to interface mixing and implantation induced defect creation in the films. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anomalous magnetic behavior is observed in Fe/Alq 3 bilayer. • Fe diffuses into Alq 3 to form 50 Å thick alloy layer at the interface. • Unexpected large effective magnetic dead layer is found at the interface. • Antiferromagnetic coupling between metallic Fe and alloyed Fe. Growth behavior and evolution of magnetism as a function of Fe thin film thickness onto organic semiconductor tris(8-hydroxyquinoline)-aluminum, (Alq 3) thin film was investigated in-situ using electrical resistance and magneto-optic Kerr effect (MOKE) measurements, respectively. The variation of electrical resistance with Fe film thickness reveals the Volmer-Weber growth of Fe on Alq 3 film. Reflection high energy electron diffraction (RHEED) pattern resembles polycrystalline BCC structure of Fe. Ex-situ x-ray reflectivity (XRR) measurement from the Fe/Alq 3 /Si sample reveals that Fe diffuses into Alq 3 to form an alloy layer of 50 Å thickness with Fe volume fraction of 0.4. In-situ MOKE study affirms anomalous magnetic behavior at the initial stage of Fe growth. Initially hysteresis loop appears and develops in a particular direction, and then vanishes at certain thickness. With further growth of Fe hysteresis loop appears again and grows in the opposite direction. The observed unusual changes in magnetic behavior as a function of Fe thickness may be explained in terms of the contribution from the magnetic Fe-Alq 3 alloy present in the intermix layer, the metallic Fe on top of Alq 3 layer, and their antiferromagnetic coupling. [ABSTRACT FROM AUTHOR]