Evidence for strong magnetoelastic effects in Ni nanowires embedded in polycarbonate membranes

The uniaxial anisotropy energy of arrays of submicronic (30-500 hm) Ni wire s synthesized by electrodeposition into cylindrical pores of track-etched p olycarbonate membranes is studied as a function of temperature. At room tem perature, the uniaxial anisotropy is equal to the shape anisotropy whereas an additional contribution, that reinforces the wire axis as an easy axis i s evidenced at low temperature. This additional contribution is demonstrate d to find its origin in magnetoelastic effects conjointly induced by the Ni and polycarbonate thermal-expansion coefficients mismatch and by the low v olume fraction of Ni in Ni/polycarbonate samples.