Experimental observations of ferroelectricity in double pyrochlore Dy₂Ru₂O₇

Abstract

Double pyrochlore Dy2Ru2O7 is synthesized and its magnetism and ferroelectricity below the Ru⁴⁺ spin ordering temperature (～100 K) are investigated. The ferroelectric transition appears at ～18 K, much higher than the Dy³⁺ spin ordering point at ～1.8 K and lower than the Ru⁴⁺ spin ordering point at ～100 K. The measured electric polarization at ～2 K is as big as 145 μC/m² in the polycrystalline samples. It is argued that the ferroelectricity is possibly ascribed to the electric dipole ordering arising from the collective monopole excitations in the Dy³⁺ tetrahedrons in prior to the Dy³⁺ spin ordering into spin-ice like state below ～1.8 K.

Graphical abstract

Keywords

pyrochlore oxides / multiferroics / magnetically induced ferroelectricity