Control of ferroelectric phase by chemical pressure in (Gd,Tb)MnO${}_3$ crystals

Abstract

We have investigated the dielectric properties of Gd${}_{1-x}$Tb${}_x$MnO${}_3$ crystals in magnetic fields to clarify the crossover between two distinct ferroelectric phases, GdMnO${}_3$-type (first-order displacive) and TbMnO${}_3$-type (second-order order-disorder). We have found that the compositional phase boundary between the phases exists around 0.3$<$$x$$<$0.4. For the $x$=0.1 sample exposed to magnetic fields above 3T, we have discovered successive ferroelectric phase transitions that occur at two different temperatures. We have determined the electric and magnetic phase diagram for $x$$=$0, 0.1, and 0.3 in the plane of temperature and field in order to demonstrate the change in the ferroelectric phases.

3 pages, 3 figures, IEEEtran, Proceedings of INTERMAG 2005, appear in IEEE Transactions on Magnetics