Pressure-induced polar phases in relaxor multiferroicPbFe0.5Nb0.5O3<

Abstract

The structural, magnetic, and vibrational properties of PbFe 0.5 Nb 0.5 O 3 relaxor multiferroic have been studied by means of x-ray, neutron powder diffraction, and Raman spectroscopy at pressures up to 30 GPa. Two successive structural phase transitions from the initial R3m polar phase to Cm and Pm monoclinic polar phases were observed at P = 5.5 and 8.5 GPa. Both transitions are associated with anomalies in pressure behavior of several stretching and bending modes of oxygen octahedra as well as Fe/Nb localized vibrational modes. The G-type antiferromagnetic order remains stable upon compression up to 6.4 GPa, assuming possible multiferroic properties of pressure-induced phases. The Néel temperature increases with a pressure coefficient (1/T N )dT N /dP = 0.012 GPa −1 . The observed pressure-induced phenomena in PbFe 0.5 Nb 0.5 O 3 are in drastic contrast with conventional multiferroics, exhibiting a general tendency towards a suppression of polar phases and/or magnetoelectric coupling under pressure.

Structural, magnetic and vibrational properties of multiferroic GaFeO3 at high pressure

“…[40]. The values of the pressure coefficients and Grüneisen parameters for the m1-m3 modes are comparable with those of rotational modes in lead ferroniobate PbFe 0.5 Nb 0.5 O 3 [30]. Therefore these modes may correspond to the rotational oxygen vibrations in octahedral and tetrahedral structural units.…”

Electric field-induced tuning of magnetism in PbFe0.5Nb0.5O3 at room temperature

“…6 , respectively, which can be ascribed to the A 1g , E g , F 1g , 4F 1u , 2F 2g , and F 2u optical phonon modes for a simplified cubic perovskite ABO 3 lattice in three dimensions with two types of cations at B-position. 17 The tentative assignments of the observed modes, as shown in Fig. 6, were made based on the previous reports for unpoled PFN ).…”

“…These changes clearly indicate change at the octahedral site. [17][18][19][20] In perspective of this, the ferroelectric ordering has enhanced. From the figure, it can be seen that in the poled sample Pb-O or O-Nb-O modes are more active than in the unpoled case.…”

“…From the figure, it can be seen that in the poled sample Pb-O or O-Nb-O modes are more active than in the unpoled case. It was reported [17][18][19] that the bands between 500 cm À1 and 900 cm À1 were of great importance for evaluating the B-site ordering in Pb-based multiferroics. Garcia-Flores et al 20 reported that peak at 791 cm À1 indicates a possible indirect magnetic nature of these modes due to the presence of Fe 3þ cations in the octahedral B site in PFN which exhibits both ferroelectric and magnetic properties.…”

Synthesis and X-ray analysis of complex ferrite YbBiNaFe2O6,5

“…На основе мультиферроика проводится широкий поиск новых материалов с сегнетоэлектрическими свойствами специфической электронной и магнитной структурами. Замещенные перовскиты на основе феррита висмута нередко сочетают сегнетоэлектрические и слабоферромагнитные свойства при доминирующем антиферромагнитном упорядочении [4,5,6].…”