Magnetic properties in a partially oxidized nanocomposite of Cu–CuCl

Magnetism of a very thin antiferromagnetic (AFM) surface CuO has been investigated with partially oxidized nanocomposites of Cu–CuCl, ~200 nm. The samples are characterized by x-ray diffraction, x-ray photoelectron spectroscopy, x-ray-excited Auger electron spectroscopy, transmission electron microscopy and magnetic measurements. The characterizations indicate that the composites have a core–shell structure. Before oxidation, it is (Cu)core/(CuCl)shell, and after oxidation it is (Cu)core/(Cu2O+CuCl+minute CuO)shell. The magnetic measurements have revealed that a ferromagnetic (FM)-like open hysteresis exists at temperatures below the freezing point, TF. In the high field region, a paramagnetic (PM) response appears without showing any sign of saturation. Also, the field dependent magnetization (M–H) measurement is PM-like at T>TF. These interesting magnetic properties are shown to arise from the AFM CuO on the outer surface. They are attributed to the uncompensated surface spins of Cu2+ and the effect of random surface potential. More interestingly, the magnetic susceptibility is greatly enhanced in the presence of Cl− anions at T

Keywords:

• Magnetism
• Auger electron spectroscopy
• Magnetic susceptibility
• Analytical chemistry
• Magnetization
• Materials science
• Nanocomposite
• Antiferromagnetism
• Ferromagnetism
• Nuclear magnetic resonance
• Paramagnetism
• freezing point

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