Magnetoresistance and structural study of electrodeposited Ni-Cu/Cu multilayers

Electrodeposition was used to produce Ni Cu/Cu multilayers by two-pulse plating (galvanostatic/potentiostatic control) from a single sulfate/sulfamate electrolyte at an optimized Cu deposition potential for the first time. Magnetoresistance measurements were carried out at room temperature for the Ni Cu/Cu multilayers as a function of the Ni Cu and Cu layer thicknesses and the electrolyte Cu2+ ion concentration. Multilayers with Cu layer thicknesses above 2 nm exhibited a giant magnetoresistance (GMR) effect with a dominating ferromagnetic contribution and with low saturation fields (below 1 kOe). A significant contribution from superparamagnetic (SPM) regions with high saturation fields occurred only for very small nominal magnetic layer thicknesses (around 1 nm). The presence of SPM regions was concluded from the GMR data also for thick magnetic layers with high Cu contents. This hints at a significant phase-separation in Ni-Cu alloys at low-temperature processing, in agreement with previous theoretical modeling and experiments. Low-temperature measurements performed on a selected multilayer down to 18 K indicated a strong increase of the GMR as compared to the room-temperature GMR. Structural studies of some multilayer deposits exhibiting GMR were performed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns of Ni Cu/Cu multilayers exhibited in most cases clear satellite peaks, indicating a superlattice structure which was confirmed also by cross-sectional TEM. The deterioration of the multilayer structure revealed by XRD for high Cu-contents in the magnetic layer confirmed the phase-separation concluded from the GMR data

Conditional Political Budget Cycles in Argentine Provinces

This paper presents evidence of electoraly-motivated changes in the budget balance, public expenditures, composition of public expenditures and provincial revenues in Argentine provinces. The empirical study is made using panel data analysis for 22 provinces during the period 1985-2001. Unconditional results show that conditioning on the alignment of provincial and federal executives (same political party in power) there is evidence of systematic changes in fiscal policies around elections. The observed changes support the predictions of rational opportunistic models of PBC. In election years, total provincial expenditures increase in aligned provinces, without affecting the fiscal balance, because to the increased discretional transfers from the federal government supporting the provincial incumbent federal revenues. By contrast, deficit increases for unaligned provinces. In addition, expenditure shifts toward current spending and away from capital spending for unaligned provinces in electoral years