Investigation on the size dependent optical and magnetic properties of DNA assisted synthesized nanoceria for next generation spintronic devices.

Cerium oxide nanoparticles or nanoceria of average crystallite size ~ 6, 9 and 14 nm were synthesized by chemical co-precipitation method using deoxyribonucleic acid (DNA) as capping agent. Size dependent structural, optical and magnetic properties of prepared samples were investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), UV-Visible diffuse reflectance spectroscopy and vibrating sample magnetometer (VSM) measurements. The increase in the value of optical band gap with decrease in particle size may be attributed to the quantum confinement effect. The saturation magnetization, coercivity and remanence increases as the particle size decreases from 14 nm to 9 nm. This is in view of the fact that increase in oxygen vacancies may produce magnetic moment by polarizing spins of f electrons of cerium ions located around them. The magnetic properties decreases below a critical size, since thermal energy can overcome the anisotropy and spontaneously reverse the magnetization of a particle from one easy direction to the other. The semiconducting properties along with room temperature ferromagnetism make DNA assisted synthesized nanoceria suitable for fabrication of next generation spintronic devices. [ABSTRACT FROM AUTHOR]