Investigation of Structural and Magnetic Properties of CoPt/CoAu Bimetallic Nanochains by X-ray Absorption Spectroscopy

Cobalt-based nanohybrid chains with diameters ranging from 20 to 50 nm have been prepared by a mild solution method. Structural, morphological, and magnetic characterization of the as-prepared products have been performed using X-ray diffraction, transmission electron microscopy, and superconducting quantum interference device apparatus. In addition, the electronic structure and the local atomic distribution were both investigated by X-ray absorption spectroscopy. Results show that different kinds of noble metals play a key role in electronic structure, atomic distribution, and magnetic properties even though they have similar morphology and long-range order structure. The changes of the electronic structure in the CoPt sample occur during the large alloying process while the CoAu sample maintains its lattice structure with negligible electronic changes. The difference between the electronic structure and the atomic distribution of these two different Co-based nanohybrid chains leads to different magnetic behaviors versus temperature.