Control of multiferroic phase in Tb1-x(Bi,La,Y)(x)MnO3

The effects of Bi-substitution in TbMnO3 on structural, magnetic, ferroelectric, and thermal properties were studied. Exotic enhancement of magnetism in Bi3+ substitution is distinguished from the simple dilution effect of magnetic Tb3+ ion with nonmagnetic Y3+ and La3+ replacement. From both structural and magnetic characterizations, we conjectured that the strong local anisotropic distortion around Bi3+ ion due to its 6s(2) tone pair modified neighboring Mn3+ spin configuration, from modulated antiferromagnetic to a ferromagnetic one and induced the formation of fierromagnetic cluster. Both the b-lattice parameter to which the modulation wave vector is parallel and the ferroelectric transition temperature turned out to be very susceptible to Bi-substitution. Controllability of both magnetic and ferroelectric phases suggests a possible route to the simultaneous occurrence of two phase transitions of different origins at the same temperature for the enhanced coupling between magnetism and ferroelectricity. (c) 2006 Elsevier B.V. All rights reserved.X111sciescopu