The investigations on ultra-fine particles of the immiscible system, such as Co-Cu and Co-Ag, are very challenging due to potential higher magnetoresistance and fundamental understanding how bulk properties transform to atomic ones. In the present study, immiscible Cu-Co nanoparticle was successfully prepared by arc-discharge technique in an atmosphere of a mixture of H2 (30%) and He (70%). Microstructures and magnetic propertied were investigated by using advanced transmission electron microscopy (TEM) and superconducting quantum interference device (SQUID). Most of the particles have sizes of 20~30 nm in diameters. High-resolution TEM observations reveal core-shell microstructures with coherent interfaces. Composition of the nano-particles was analyzed by nano-probe energy dispersive X-ray (EDX) analysis, revealing microstructure of cores of Cu-Co solutions covered by oxide shells. Co particles were occasionally observed. The magnetic properties have been analyzed by temperature dependence of magnetization, zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements. The loop shift in the hysteresis loop indicates the existence of the exchange bias between ferromagnetic and antiferromagnetic components at low temperatures. A block temperature about 180 K has been observed for as-deposited nanoparticles. For the annealed nanoparticles, the thermal magnetization at low temperatures is satisfied with Bloch’s law.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/3529 must be provided.

1. Microstructures and mechanical property of Ni processed by high-pressure torsion and their evolution upon annealing
2. Composition gradients surrounding Ni₄Ti₃ precipitates in a Ni-rich NiTi alloy studied by EELS, EFTEM and EDX