Co nanowires (NWs) and nanotubes (NTs) with same length and different diameter have been deposited in anodized aluminum oxide templates by electrodeposition method at the room temperature. The Co NWs show hcp structure while Co NTs show poor crystalline with no strong texture. The spontaneous magnetization of the Co NWs was found to be parallel to the nanowires, while Co NTs have a transverse spontaneous magnetization. Magnetization reversal occurs by curling mode in Co nanotubes while nucleation mode in Co nanowires. Temperature dependent magnetic properties show that the thermal energy decreases at low temperature causing an increase in coercivity and saturation magnetization. The dominance of shape anisotropy in case of Co NWs is manifested by the weak temperature dependence of the enhanced coercive field. Magnetostatic interactions and magnetocrystalline anisotropy is found dominant in case of Co NTs due to their distinct geometry.
Bibliographical noteFunding Information:
The project was supported by the State Key Project of Fundamental Research, Ministry of Science and Technology (MOST No. 2010CB934400) and National Natural Science Foundation (NSFC Nos. 10874225 and 50721001) and Microfabrication Centre of IOP. Naeem Ahmad is especially thankful to Higher Education Commission of Pakistan for financial support.