Amorphous hafnium oxide ͑HfO x ͒ is deposited by sputtering while achieving a very high k ϳ 30. Structural characterization suggests that the high k is a consequence of a previously unreported cubiclike short range order in the amorphous HfO x ͑cubic k ϳ 30͒. The films also possess a high electrical resistivity of 10 14 ⍀ cm, a breakdown strength of 3 MV cm −1 , and an optical gap of 6.0 eV. Deposition at room temperature and a high deposition rate ͑ϳ25 nm min −1 ͒ makes these high-k amorphous HfO x films highly advantageous for plastic electronics and high throughput manufacturing.

A novel rf sputtering technology in which a high density plasma is created in a remote chamber has been used to reactively deposit zinc oxide (ZnO) and indium zinc oxide (IZO) thin films at room temperature from metallic sputtering targets at deposition rates ∼50 nm min −1 , which is approximately an order of magnitude greater than that of rf magnetron sputtering. Thin film transistors have been fabricated using IZO with a maximum processing temperature of 120 • C, which is defined by the curing of the photoresist used in patterning. Devices have a saturated field effect mobility of 10 cm 2 V −1 s −1 and a switching ratio in excess of 10 6 . Gate bias stress experiments performed at elevated temperatures show a consistent apparent increase in the field effect mobility with time, which is attributed to a charge trapping phenomenon.

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In this work we report on an extensive and detailed study of exchange bias systems consisting of two ferromagnetic layers deposited with an antiferromagnetic layer of IrMn between them. Systems with two different ferromagnetic layers have been studied in which sample 1 had CoFe layers of different thicknesses and sample 2 had not only ferromagnetic layers of different thicknesses but also the composition of the upper ferromagnetic layers was changed from CoFe to NiFe. In both the samples the antiferromagnetic layer thickness was maintained constant at 5 nm, NiCr seed and capping layers (5 nm) were used on all samples. Such a system is of considerable interest as the properties of each ferromagnetic layer are affected by the same antiferromagnet. However differences in behaviour will occur due to the nature of the interfaces between the different layers as well as other parameters such as the ferromagnetic layer thickness. We have conducted a study of thermal activation effects in these systems where both or a single ferromagnetic layer can be reversed whilst the system is heated. We find that we can differentiate between bulk and interface effects indicating that the role of spin disorder at the interface is crucial in determining the final value of the exchange bias.

Abstract-We discuss a method for the determination of activation volumes of reversal in perpendicular media. This method does not require correction for the self-demagnetizing field normally associated with these media. This is achieved by performing time dependence measurements at a constant level of magnetization. From the difference in time taken for the magnetization to decay to a fixed value at two fields separated by a small increment 1 , the activation volume can be determined. We report data for both CoCrPt alloy films and a multilayer film, typical of those materials under consideration for use as perpendicular media. We find activation volumes that are consistent with the hysteresis curves of the materials. The activation volume scales qualitatively with the exchange coupling. The alloy films have significantly lower activation volumes, implying that they would be capable of supporting a higher data density.