Multiferroic, Phonon and Optical Properties of Pure and Ion-Doped YFeO Nanoparticles.

The magnetic, electric, phonon and optical properties of pure and ion-doped orthorhombic YFeO3 nanoparticles are studied for the first time theoretically. The spontaneous magnetization Ms in YFeO3 decreases with decreasing particle size. Ms is also shape dependent. The magnetization increases by Co and Er ion doping and decreases by Ti doping, which is caused by the different strain which appears in the nanoparticles and changes the exchange interaction constants in the doped states. The phonon energy for the Ag mode ω = 149 cm-1 and their damping decreases or increases with increasing temperature, respectively. Both show a kink near the Neel temperature, TN, which disappears by applying an external magnetic field. The influence of different ion doping on the band gap energy is also discussed. The doping effects can be used for different applications.