Magnetoelectric effect and low-temperature phase transitions in YMn₂O₅

Abstract

A possibility of ferroelectricity has been proposed in some low temperature phases of the oxides of the series RMn₂O₅ (R = a rare earth from Nd to Lu, Y or Bi). YMn₂O₅ is unusual in this series, because Y³⁺ is non-magnetic. We made dielectric, magnetic and magnetoelectric measurements on single crystals of this oxide to detect two electric transitions at 39 K and 19 K.

These transitions are accompanied with anomalies in the dielectric constant and the magnetic and the magnetoelectric susceptibilities. Particularly, the sign of the magnetoelectric susceptibility is switched below 19 K, depending on the sense of the electric field applied during cooling the sample down to 4.2 K. This fact indicates that YMn₂O₅ possesses spontaneous polarization at least below 19 K.

Key Words:

• Magnetoelectric effect
• polar-non-polar transition
• ferroelectricity
• rare earth manganese oxide
• YMn₂O₅
• magnetic ordering