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Discusses the correlation between chemistry and the amount of mixing in bilayers submitted to ion bombardment. Importance of thermodynamic forces in interfacial mixing during ion bombardment; Information on the chemical aspects of the interactions; Correlation between electronegativity differences and the mixing effects.

Examines surface hardness enhancement in ion-implanted amorphous carbon. Experimental details; Techniques and methodologies used for compositional analysis including Rutherford backscattering; Results and discussion.

We describe the concept of using irradiation with light energetic ions in conjunction with a mask to define the edges of giant magnetoresistive sensors without milling. The irradiated material undergoes substantial interfacial mixing, and consequent loss of magnetoresistance (MR), accompanied by small changes in resistivity, and no significant change in magnetic moment. The ion species and energy may be chosen to minimize lateral scattering as they pass through the sensor film. Modeling of a perfect mask edge above a sensor film of thickness ~ 240 [Angstrom] irradiated with a well-collimated ion beam indicates that sensor edge definition of [+ or -] 20 [Angstrom] is achievable--a vast improvement over sensor edges generated using ion milling, which may run to hundreds of [Angstrom]ngstroms in width. Experimental data from irradiation of typical NiO, IrMn, NiMn and PtMn-based spin valves using 700 keV [N.sup.+] ions indicate that doses between [10.sup.15] and [10.sup.17] ions/[cm.sup.2] are sufficient to diminish the MR of the films to below 5% of the as-grown value. Changes in MR caused by the irradiation are stable against annealing at temperatures typical for setting these sensors. Index Terms--Ion irradiation, magnetic films and devices, magnetic sensors, spin valves.

L10 FePt nanoparticle assemblies consisting of a few layers of 4-nm-diameter particles, are a potential data storage medium beyond 1 Tbit/in2. However, annealing at temperatures >500 °C is required to form the high anisotropy L10 phase. Recent studies have shown a substantial drop in magnetization for Tanneal>650 °C. We show that this reduction in magnetization is due to silicide formation as a result of a chemical reaction with the native oxide or Si substrate. We also show that full L10 ordering is established only after annealing at 725 °C for 60 min and note that particle agglomeration occurs under these conditions. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Co/Pt multilayer films with perpendicular magnetic anisotropy and large out-of-plane coercivities of 3.9–8.5 kOe have been found to undergo a spin reorientation transition from out-of-plane to in-plane upon irradiation with 700 keV nitrogen ions. X-ray reflectivity experiments show that the multilayer structure gets progressively disrupted with increasing ion dose, providing direct evidence for local atomic displacements at the Co/Pt interfaces. This effectively destroys the magnetic interface anisotropy, which was varied by about a factor of 2, between K[sub S]≅0.4 erg/cm[sup 2] and K[sub S]≅0.85 erg/cm[sup 2] for two particular films. The dose required to initiate spin-reorientation, 6×10[sup 14] N[sup +]/cm[sup 2] and 1.5×10[sup 15] N[sup +]/cm[sup 2], respectively, scales with K[sub S]. It is roughly equal to the number of Co interface atoms per unit interface area contributing to K[sub S]. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have used ion beam irradiation through a silicon stencil mask to alter the magnetic properties of Co/Pt multilayer and FePt chemically-ordered superlattice films. In both systems, ion irradiation disorders the as-grown films which results in a reduction of the magnetic anisotropy. Regularly spaced micrometer-sized regions of magnetically altered material have been produced over areas of a square millimeter. These magnetic structures have been observed by magnetic force microscopy. By stepping the mask during irradiation, features at twice the spatial frequency of the mask holes have been produced. Such patterned magnetic films are of interest for application in high-density magnetic recording. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Comparing alkyl chains can be good hole conductors as long as the chains are chemically bonded to the contacts. The results show that in the absence of a chemical bond between the alkyl chain and the metal, not only is the conductivity lower but the charge-transfer mechanism is also changed.

A simple chemical process of assembling FePt nanoparticles with control on assembly thickness and dimension is described. The process can be applied to any sized and shaped substrate thus offering a great potential for FePt-based nanodevice fabrication.

Doping ferromagnetic nickel–iron alloys with chromium causes the Curie temperature to be reduced. We have demonstrated that solid state solutions of Ni–Fe–Cr can be formed by implanting Cr ions into ferromagnetic NiFe alloy films, thus creating paramagnetic films. We find that the magnetic moment and coercivity decrease steadily with Cr+ dose, reaching zero at room temperature with the onset of paramagnetism. Using Cr+ implantation in conjunction with a lithographic mask we have patterned continuous Ni80Fe20 films into separate regions that are ferromagnetic and paramagnetic at room temperature. This magnetic patterning process may have applications for the manufacture of magnetic write heads, such as for the notching process used to constrain the stray field from the write gap. [ABSTRACT FROM AUTHOR]

In this letter, a direct measurement of a refractive index change in potassium gadolinium tungstate (KGW) created by a low-dose ion implantation of 1 MeV hydrogen ions is reported. The characterization was performed using both microreflectivity and Raman spectroscopy measurements. The microreflectivity results show both negative and positive changes in refractive index in the damage region when measuring refractive index along different polarization axes. Micro-Raman spectroscopy analysis shows preservation of the Raman characteristics of KGW in the nondamaged crystal regions. These results show that ion implantation in KGW has a great potential for fabricating waveguide structures in Raman-based photonic devices. [ABSTRACT FROM AUTHOR]