Study of the magnetization reversal in individual nickel nanowires

The magnetization reversal of Ni nanowires was studied by anisotropic magne toresistance measurements at temperatures between 15 and 300 K. The wires, synthesized by electrodeposition in a nanoporous polycarbonate membrane, ar e regular cylinders 22 mu m long with a diameter of 75 or 35 nm. The nuclea tion field was measured on individual nanowires as a function of the angle between the applied field and the wire axis. The results are quantitatively analyzed using classical magnetization reversal theories. Measurements of the nucleation field first obtained as a function of temperature evidence a n extra uniaxial anisotropy induced by the contraction of the membrane at l ow temperature. Combining SQUID measurements and x-ray diffractometry at di fferent temperatures, a clear picture of the large magnetoelastic effect wa s obtained. (C) 2000 American Institute of Physics. [S0021-8979(00)03902-5] .