Ferroelectric properties controlled by magnetic fields in DyMn2O5

TL;DR

This study demonstrates that external magnetic fields can induce and modify ferroelectric states in DyMn2O5, revealing complex phase transitions and strong coupling between magnetic and electric properties.

Contribution

It uncovers the magnetic field-induced ferroelectric phases in DyMn2O5 and links these to Dy f-moment transitions and Mn spin structure interactions.

Findings

Multiple ferroelectric phases identified between 43 K and 4 K.

Magnetic field induces ferroelectricity in the low-temperature paraelectric phase.

Ferroelectric phases are strongly tied to Dy and Mn magnetic interactions.

Abstract

Cross-correlation between magnetic and dielectric properties has been attracting renewed interest because of the fundamental as well as technological importance of controlling the electric (magnetic) polarization by an external magnetic (electric) field. Here, we report the novel phenomenon that an external magnetic field induces and/or modifies ferroelectric states in a magnetic material, DyMn2O5. Measurements of temperature dependence of hysteretic polarization curves, pyroelectric current, specific heat, optical second harmonic generation, and x-ray superlattice peaks have revealed successive phase transitions between 43 K and 4 K, accompanying three ferroelectric phases. The zero-field lowest-temperature phase (<8 K) induced by the Dy-moment ordering is a reentrant paraelectric state, but is turned to a ferroelectric state with increasing the magnetic field. The phenomenon is closely related to the metamagnetic transitions of the Dy f-moment, indicating that all the ferroelectric phases of this material are strongly tied to the antiferromagnetic Mn spin structure affected by the f-d exchange interaction. The electric phase diagram for DyMn2O5 is presented in the plane of temperature and magnetic field.