Anticorrelation between ferromagnetism and ferroelectricity in perovskite manganites

Abstract

Magnetic and dielectric properties have been investigated for a mixed-crystal system ${\mathrm{Tb}}_{1-x}{\mathrm{Gd}}_x\mathrm{Mn}{\mathrm{O}}_3$ in between $\mathrm{Tb}\mathrm{Mn}{\mathrm{O}}_3$ with ferroelectric and incommensurate antiferromagnetic (AFM) orders and $\mathrm{Gd}\mathrm{Mn}{\mathrm{O}}_3$ 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 $x\text{−}T$, $B\text{−}T$, and $x\text{−}B$ 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.