Control of the ferroelectricity in a metastable state for orthorhombicRMnO₃crystals

Abstract

We have investigated orthorhombic RMnO 3 (R=(Gd 1−y Tb y )) crystals near the phase boundary between the paraelectric A-type-antiferromagnetic (AF) phase (PA) and the ferroelectric transverse-spiral-AF one (FS). The spiral AF structure breaks inversion symmetry and induces the ferroelectric polarization through the inverse Dzyaloshinskii-Moriya (DM) interaction. We have found that the PA-FS phase boundary is located at around 0.15<y<0.2. In y=0.15 compound, PA and FS phases appear in cooling scan, while FS is not observed in warming scan. This result suggests that FS observed in y=0.15 is a metastable state arising from the competition between PA and FS. Furthermore, we demonstrate the phase control between these competing phases by the application of the external magnetic field and external quasihydrostatic pressure.

Persistent and reversible phase control in GdMnO3near the phase boundary

“…Let us move on to the magnetic field effect on the ferroelectricity. As already reported in our previous reports [7,8,9] and other groups' [1, 2, 10], the magnetic field along the b axis (H b ) stabilizes the ferroelectric phase. The observed ferroelectric transition temperatures are drastically increased by application of H b , as shown in the Fig.…”

New orthorhombic multiferroics R1–xYx MnO3 (R = Eu, Gd)

“…Recently, new interesting properties of some RMnO 3 manganites have been revealed which are related to a change of their magnetic structure from a canted antiferromagnetic layer ordering (A y F z ) to a spatially modulated (sinusoidal) antiferromagnetic one for R = Eu, Gd, Tb, Dy caused by a frustration of exchange interactions due to decreasing of the R-ionic radii r R from La to Dy [1][2][3][4][5][6]. It results in the appearance of electric polarization below the spontaneous incommensurate-commensurate (IC-C) transition at temperature T lock < T N = 45 -40 K and unusual magnetic-field-induced transitions accompanied by reorientation or suppression of electric polarization for R = Tb, Dy [1,2] and Gd [7,8]. In this work we have realized the above-mentioned tendency to form multiferroic states in the substituted compounds Eu 1-x Y x MnO 3 and Gd 1-y Y y MnO 3 , where an average r R and parameters of Mn-O-Mn bonds are continuously adjusted by the content of Y with a smaller ionic radii thus permitting a gradual control of magnetic and electric ground states.…”

Gigantic magnetocapacitance and magnetostriction in ferroelectric antiferromagnet GdMnO/sub 3/

“…Furthermore, the magnetic ferroelectricity has been reported at the IC-C (lock-in) magnetic transition temperature in TbMn03 [3]. Recently, we have found that the ferroelectric phase exists below 13K in the A-type AF GdMn03 crystal [4] [5]. The spontaneous polarization was confirmed to be present along a axis in the orthorhombic Pbnna setting.…”