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Magnetization reversal in nickel nanowires was studied using anisotropic magnetoresistance measurements.

A study was conducted to examine the electrodeposition of patterned magnetic nanostructure devices supporting submicronic dimensions using the template technique. The faces of a doped silicon substrate were metallized by sputtering gold on chromium before pure multilayers were electrodeposited into the cavities. Experimental results indicated that the template method can effectively fabricate magnetic metallic nanostructures.

We report measurements on the thermal conductivity and thermoelectric power of granular Co20Ag80 solids annealed at various temperatures. Thermal conductivity is dominated by its electronic contribution and the Wiedemann-Franz law is found to be satisfied between 2K and 300K, which is mainly ascribed to dominant large-angle elastic scattering processes. The thermoelectric power is negative and is considerably reduced by the annealing process. Giant magnetothermal conductivity and giant magnetothermopower are found to be correlated with the giant magnetoresistance.

The conductance and magnetoresistance measurements in magnetic Ni-Ni and Co-Ni nanocontacts prepared by electrodeposition within the pores of a track-etched polymer membrane is presented. The results show that the magnetoresistance is caused by a local effect in the vicinity of the nanoconstriction.

A multiprobe connection setup has been used to study the magnetoresistance (MR) of isolated electrodeposited ferromagnetic cobalt nanowires. The MR hysteresis loops taken along different segments of the same 60-nm-diameter Co wire are found to be completely different, pointing out local inhomogeneity of the magnetic anisotropy along the same wire. These results are corroborated both by magnetic force microscopy (MFM) and transmission electron microscopy (TEM) experiments, showing a mixing of parallel and perpendicular c-axis orientations along the wire. Index Terms--Lithography, magnetism, magnetoresistance, nanowires.

The effect of the electrolyte acidity, or pH, on the structural and magnetic properties of electrodeposited cobalt nanowires has been studied. The main result is that as the pH is lowered from 3.8 down to 2.0, a microstructural change is induced. Ferromagnetic resonance measurements show that at high pH, Co presents an hcp phase with the c-axis aligned perpendicular to the wires, whereas at low pH, a more disordered hcp structure is observed. From the resonance line shape analysis, it is shown that for low-pH Co, no grains oriented with the c-axis perpendicular to the wire are present. The resulting magnetic properties show that for high-pH samples, the effective anisotropy field is weaker than that of the low-pH samples due to the competition between shape anisotropy and the cobalt c-axis magnetocrystalline anisotropy. Index Terms--Electroplating, magnetic resonance, magnetic structure.

Research into the microwave absorption characteristics of arrays of magnetic nanowires electrodeposited in nanoporous membranes is presented. It was found that the remanent and high field ferromagnetic resonance frequency and frequency range can be easily tuned as a function of the membrane packing density and the magnetization of the material.

Using low density arrays of bistable magnetic nanowires as a model dipolar system, it is shown that the dipolar interaction field coefficient can be measured from the remanence curves as well as from other functions of the isothermal remanent magnetization and the DC demagnetization remanence obtained as an affine transformation of the Wohlfarth relation. Based on mean field arguments, these measurements are used to subtract and remove the contribution of the configuration dependent dipolar interaction field from the major loop and remanence curves. The corrected remanence curves are first used to obtain the intrinsic switching field distribution of the nanowire array and then to validate this approach showing that they yield results consistent with the Wohlfarth relation for an assembly of noninteracting particles, thus providing a self-consistent procedure to verify the measured values of the interaction field and its removal from the measurements. [ABSTRACT FROM AUTHOR]

The microwave power density absorbed in the normal state by continuously irradiated superconducting Nb and NbN nanostrips is extracted from their electrical transport properties. The procedure is based on the reduction of the retrapping current (i.e., the minimum applied current required to sustain a dissipative region inside a superconducting microbridge) that results from the microwave dissipation. The power effectively absorbed by the nanostrips varies linearly with the input power level and falls in the μWμm-3 range. At a given microwave frequency, the relation between the input power and the absorbed power does not depend on the coolant temperature. In addition, the upper limit of the detection range is given by the heat removal capabilities through the substrate. When the absorbed microwave power exceeds this temperature-dependent heat removal threshold, normal hotspot domains are stabilized down to zero bias current. The determination of the microwave power absorbed by superconducting samples in the normal state may be of practical interest in the field of incident power detection. [ABSTRACT FROM AUTHOR]