Exchange coupling has been observed in a ferromagnet (FM)/antiferromagnet (AF) bilayer with Curie temperature (TC)≪Néel temperature (TN) in the regime of TTN. With increasing temperature, HC vanishes at TC, whereas HE persists to TN. The results show that the exchange coupling can be established in FM/AF bilayers regardless of the relative values of TC and TN. © 1999 The American Physical Society.

The contrasting effects of ion implantation and thermal annealing on structural and magnetic properties of Co/Pd multilayers have been studied. Ion implantation causes local damage to the multilayers, resulting in enhanced magnetization due to the polarization of the neighboring Pd. Thermal annealing generates massive interdiffusion across the interfaces into the formation of Co-Pd alloys with a lower magnetization. Effects on coercivity and remanence have also been studied.

The effect of Fe doping (<20%) on the Mn site in the ferromagnetic ((Formula presented)) and the antiferromagnetic ((Formula presented)) phases of (Formula presented) has been studied. The same ionic radii of (Formula presented) and (Formula presented) cause no structure change in either series, yet conduction and ferromagnetism have been consistently suppressed by Fe doping. Colossal magnetoresistance has been shifted to lower temperatures, and in some cases enhanced by Fe doping. Doping with Fe bypasses the usually dominant lattice effects, but depopulates the hopping electrons and thus weakens the double exchange. © 1996 The American Physical Society.

We have successfully fabricated multilayered Co/Cu nanowires with different diameters and various layer thicknesses by electrodeposition. They display a large perpendicular giant magnetoresistance up to 11% at room temperature and 22% at 5 K. The spin-flip diffusion length has been directly measured to be about 210 for this system. © 1995 The American Physical Society.

Trigonal-axis oriented single-crystal Bi thin films have been made by electrodeposition followed by suitable annealing. Very large magnetoresistance with ratios as much as 1500 at 5 K and 2.9 at 300 K under 5 T, Shubnikov-de Haas oscillations, and finite-size effects have been observed. © 1999 The American Physical Society.

Arrays of semimetallic Bi nanowires have been successfully fabricated by electrodeposition. Each nanowire consists of elongated Bi grains along the wire direction. Very large positive magnetoresistance of 300% at low temperatures and 70% at room temperature with quasilinear field dependence has been observed. These features are desirable for wide-range field sensing applications. © 1998 American Institute of Physics.