Abstract
Magnetoelectric phase diagrams have been investigated for rare-earth manganites with orthorhombically distorted perovskite structure, (, Tb, and Dy). A variety of magnetic and electric phases emerge with varying -site ion, temperature, and magnetic field in these systems. The magnetoelectric phase diagram varies sensitively with the direction of a magnetic field relative to the crystallographic axes. Although the ground state of with the largest ionic radius of is not ferroelectric in zero magnetic fields , a ferroelectric phase with electric polarization along the axis appears by applying along the axis. Both and show a ferroelectric order with along the axis even at below a lock-in transition temperature where nonzero wave vectors for magnetic and lattice modulations become nearly constant. These systems also exhibit a flop of the ferroelectric polarization ( to ) when is applied along the or axis. By contrast, the application of above along the axis completely suppresses the ferroelectricity in . Possible origins of the observed evolution of magnetoelectric phases are discussed in consideration of magnetism and lattice distortion in the perovskite rare-earth manganites.
12 More- Received 22 November 2004
DOI:https://doi.org/10.1103/PhysRevB.71.224425
©2005 American Physical Society