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A detailed study of magnetic properties and room temperature memory effect in wet chemically prepared Ni<inf>0.2</inf>Cu<inf>0.8</inf> nanostructured alloy
Journal
Journal of Magnetism and Magnetic Materials
ISSN
03048853
Date Issued
2020-03-15
Author(s)
Dhara, Susmita
Mahajan, Avinash V.
Abstract
We present the magnetic properties of nanostructured Ni0.2Cu0.8 granular alloy prepared by a chemical reduction process. Zero-field-cooled and field cooled magnetization studies show branching due to the presence of superparamagnetism. The large particle size distribution in our sample is reflected in a broad blocking temperature distribution which on the higher side extends to 390 K. Magnetic field dependence of magnetization shows a superparamagnetic component accompanied with a ferromagnetic part at low temperature with prominent hysteresis loops exhibited at temperatures 2–50 K. The average magnetic moment of nickel (0.5μB) is smaller than its expected ferromagnetic saturation value (0.6μB) indicating that not all Ni atoms contribute to ferromagnetism. The magnetization data are analyzed in terms of an existing core–shell nanoparticle model. The study demonstrates that the overall behavior of the system is that of an assembly of non-interacting superparamagnetic (SPM) particles exhibiting the magnetic memory effect in relaxation dynamics, which has been observed using different experimental protocols, and persists even up to room temperature.