Evolution of Magnetic Interactions From Non-Magnetic Amorphous Ni-Cu@SiO2 Composite

In the present study, we have investigated the structural and magnetic properties of disordered Ni72Cu28@SiO2 composites synthesized by modified sol–gel method with varying SiO2 content. The nanocrystallites of Ni72Cu28 evolved from amorphous composite on heat treatment. Fourier transform infrared (FTIR) and transmission electron microscopy (TEM) results revealed that Ni–Cu particles are embedded in silica matrix. Particle size and its distribution are significantly affected by increasing silica content in the composite. The field and temperature-dependent magnetization [zero field cooled (ZFC) and field cooled (FC)] measurements indicate a superparamagnetic (SPM) behavior with particle size distribution and corroborate well with the results obtained from TEM. Our present work shows that the magnetic interaction can be tuned by varying the SiO2 content.