Magnetic behavior of an array of cobalt nanowires

Cobalt nanowires have been electrodeposited into the pores of Anodisc(TM) a lumina membranes after placing on one side a layer of sputtered copper, whi ch acts as electrode and substrate during the electrodeposition. Nanowires are 60 mm long, 170-220 mu m in diameter depending on the size of the pores of the alumina membrane. This array of nanowires exhibits uniaxial magneti c anisotropy related to the particular shape of each individual nanowire. O n the contrary to the expected behavior in a uniaxial magnetic system, the coercivity of the array exhibits a maximum when the applied field is in a p erpendicular direction with respect to the easy axis. This magnetic behavio r is analyzed considering dipolar interactions among nanowires, and the mag netization of the array is obtained as a function of the magnetic character istics of each nanowire using an iterative method. (C) 1999 American Instit ute of Physics. [S0021-8979(99)63208-X].