Magnetic, Optical and Phonon Properties of Ion-Doped MgO Nanoparticles. Application for Magnetic Hyperthermia

Abstract

The influence of size and doping effects on the magnetization M, phonon (Formula presented.) and band gap energy (Formula presented.) of MgO nanoparticles is studied using a microscopic model. The room-temperature ferromagnetism is due to surface or/and doping effects in MgO nanoparticles (NPs). The influence of the spin–phonon interaction is discussed. M increases with decreasing NP size. M and (Formula presented.) can increase or decrease by different ion doping (Co, Al, La, Fe) due to the different strain that appears. It changes the lattice parameters and the exchange interaction constants. We found that MgO NP with size of 20 nm and Fe- or Co-doping concentration x = 0.1 and x = 0.2, respectively, have a Curie temperature (Formula presented.) = 315 K, i.e., they are appropriate for application in magnetic hyperthermia, they satisfy the conditions for that. The energy of the phonon mode (Formula presented.) = 448 cm (Formula presented.) increases with decreasing NP size. It increases with increasing Co and Fe, or decreases with Sr ion doping.