Magnetoelectric relaxor

Abstract

The site and charge disordered solid solution 0.8Pb(Fe1∕2Nb1∕2)O3–0.2Pb(Mg1∕2W1∕2)O3 is a magnetoelectric relaxor which shows broad and frequency dependent maxima both in the electric as well as in the magnetic susceptibilities. The Vogel-Fulcher-type electric relaxor freeze-out is accompanied by a significant magnetic anomaly demonstrating magnetoelectric coupling. Thus, a magnetoelectric effect is observed in a system exhibiting only mesoscopic and no long range order.

Room-temperature single phase multiferroic magnetoelectrics: Pb(Fe, M)x(Zr,Ti)(1−x)O3 [M = Ta, Nb]

“…The room-temperature orthorhombic C 2v point group symmetry inferred from earlier x-ray diffraction studies is confirmed via TEM, and the primitive unit cell size is found to be the basic perovskite Z ¼ 1 structure of BaTiO 3 , also the sequence of phase transitions with increasing temperature from rhombohedral to orthorhombic to tetragonal to cubic mimics barium titanate. It has been known for several years [1][2][3][4][5][6] that the perovskite oxides PbFe 1/2 Ta 1/2 O 3 (PFT), PbFe 1/2 Nb 1/2 O 3 (PFN), and PbFe 2/3 W 1/3 O 3 (PFW) are multiferroics with long-range magnetic ordering near or above room temperature. Our earlier studies showed [7][8][9][10][11][12][13][14][15][16][17] that solid solutions of these materials with PbZr x Ti 1Àx O 3 and pure PbTiO 3 yielded single-phase ferroelectric crystals whose weak ferromagnetism persists to room temperature or above.…”

Room-temperature multiferroic magnetoelectrics

“…3 ('PZT') have been under study for several years in a San Juan-Cambridge-Belfast collaboration that now includes Delhi. [32][33][34][35][36][37][38][39][40] The reason is shown in the Venn diagram in Figure 4. Each of the Fe-compounds is ferromagnetic at modest temperatures and ferroelectric at low temperatures.…”

Phonon anomalies and phonon-spin coupling in oriented PbFe0.5Nb0.5OCorrea1, Kumar2, Priya3 et al. 2011Phys. Rev. B570300View full textAdd to dashboardCite

“…The temperature evolution of the dielectric spectra of PFN film showed three anomalies: (1) a kink near the Neel temperature (~170 K); (2) a diffuse phase transition (327 K-380 K) with frequency dispersion near the temperature at which the dielectric maxima occur; and (3) an almost frequency-independent maximum at 600 K, suggesting weak magnetoelectric (ME) coupling, relaxor behavior, and a structural phase transition, respectively 9 . Dielectric properties and magnetic hysteresis revealed the coexistence of relaxor ferroelectricity and weak ferromagnetism at room temperature in PFN films 8,9,17 . Although neither the relaxor state nor the magnetic transitions are accompanied by a transition to a homogeneous single-phase state with long-range order, we still observe phonon anomalies in the vicinity of T N and T m .…”

“…Although PFN does not exhibit B-site cation ordering, it shows normal long-range dipole order in the FE phase 16 of single crystals and ceramics. However, PFN films have been reported as magnetoelectric relaxors, that is, having a simultaneous frequency dispersion of both the electrical and magnetic susceptibilities 17 -a relaxor ferroelectric with weak ferromagnetic properties 8,9 . The detailed structural, dielectric, and magnetic properties of the PFN films are reported elsewhere 9 .…”