Anticorrelation between ferromagnetism and ferroelectricity in perovskite manganites

Magnetic and dielectric properties have been investigated for a mixed-crystal system Tb1-xGdxMnO3 in between TbMnO3 with ferroelectric and incommensurate antiferromagnetic (AFM) orders and GdMnO3 with paraelectric and canted AFM (weakly ferromagnetic) states, as functions of x, temperature T, and magnetic field B applied along the c axis. A systematic study on the magnetic and electric phase diagrams in the x-T, B-T, and x-B planes has revealed important interplay between Mn d-electron spins and Gd f-electron moments. A clear anticorrelation between the (weak) ferromagnetism and the ferroelectricity is observed near the phase boundaries.