Differences between the multiferroic properties of hexagonal and orthorhombic ion-doped YFeO3 nanoparticles.

The multiferroic properties of ion-doped hexagonal and orthorhombic YFeO3 (YFO) nanoparticles (NPs) are studied theoretically. The magnetization M s in h-YFO NPs increases, whereas for o-YFO NPs it decreases with decreasing NP size. In the dielectric constant (DC) both h- and o-YFO have a peak around T C 1 ∼ 4 5 0 and 460 K, respectively, but only in h-YFO an anomaly appears at T C 2 ∼ 3 0 0 K in the DC and the polarization which could be connected with a possible P 6 3 m c – P 6 3 c m phase transition. The polarization in pure and Bi-doped o-YFO NPs increases with increasing magnetic field. M s (x) is studied by doping of a o-YFO NP with Ti 4 + ions at the octahedral Fe 3 + sites. M s (T) in undoped YFO shows a small kink at T C 1 ∼ 4 5 0 K, whereas in the doped YFO it shows at ∼ 480 K. By different ion doping on the Y or Fe sites in YFO there is a transformation from the h- to the o-phase or vice versa. In Mn-doped o-YFO a spin-reorientation transition appears. The bandgap of h-YFO is smaller compared to that of o-YFO. [ABSTRACT FROM AUTHOR]