Understanding the physical properties of magnetic nanowires (NWs) is of crucial importance due to their potential technological applications. In this paper we report a detailed study on the temperature dependence of the magnetic [$M\left(T\right)$] and magnetotransport [$\text{MR}\left(T\right)$] properties of Ni and NiFe NWs grown on anodic aluminum oxide templates. While the behavior of the NiFe NWs reflected the presence of a strong shape anisotropy, Ni NWs showed anomalous $M\left(T\right)$ and $\text{MR}\left(T\right)$. The deviations from the expected $M\left(T\right)$ and $\text{MR}\left(T\right)$ behaviors suggest a reorientation of the magnetization easy axis with decreasing temperature. We then extracted the temperature variation of the angle between the magnetization and the NW longitudinal axis, and found an increase from 0${}^{\circ }$ at 370 K to $\sim$43${}^{\circ }$ at 5 K. Using a fourth-order magnetic anisotropy energy model we were able to successfully explain our results and show that the presence of a magnetoelastic anisotropy contribution due to the compressive stress acting in the NWs is the main origin of the observed magnetization reorientation.

• Received 11 March 2011

DOI:https://doi.org/10.1103/PhysRevB.84.014410