Charge-Stripe Order in the Electronic FerroelectricLuFe2O4

Abstract

The structural features of the charge ordering states in LuFe 2 O 4 are characterized by in-situ cooling TEM observations from 300K down to 20K. Two distinctive structural modulations, a major q 1 = (1/3, 1/3, 2) and a weak q 2 =q 1 /10 + (0, 0, 3/2), have been well determined at the temperature of ~20K. Systematic analysis demonstrates that the charges at low temperatures are well crystallized in a charge stripe phase, in which the charge density wave behaviors in a non-sinusoidal fashion resulting in elemental electric dipoles for ferroelectricity. It is also noted that the charge ordering and ferroelectric domains often change markedly with lowering temperatures and yields a rich variety of structural phenomena.

Photoluminescence in electronic ferroelectric Er1−xYbxFe2O4

“…We interpret this as due to the strong local field which is characteristic of ferroelectric materials. It is well known that LuFe 2 O 4 has a layered lattice structure, and its spontaneous electric polarization due to charge-frustration is prominent with a direction along the c-axis [1,4]. Thus, based on our analysis, our PL measurement confirms the existence of strong local field in the RFe 2 O 4 multiferroic materials.…”

“…The electronic ferroelectricity coupled with magnetism in charge-/spin-frustrated RFe 2 O 4 (R=Y, Er, Yb, Tm and Lu) materials have attracted much attention in recent studies [1][2][3][4][5]. Experimental measurements in this kind of materials have revealed a notable interplay among charge, spin and the crystal lattice.…”

“…1a). The origin of ferroelectricity in this kind of material is fundamentally correlated with the disappearance of the inversion symmetry as a consequence of the Fe 3+ and Fe 2+ charge ordering of W layer [1,[4][5]. Experimental studies revealed a large spontaneous polarization of about 0.24 Cm -2 in LuFe 2 O 4 [1], which is comparable to the polarization of 0.26 Cm −2 in BaTiO 3 [6] Erbium-doped ferroelectric materials have attracted much interest in recent years for their unique optoelectronic properties [7][8][9].…”

Nonlinear current-voltage behavior and electrically driven phase transition in charge-frustrated LuFe 2 O 4

“…In order to obtain the LuFe 2 O 4 single crystals, the LuFe 2 O 4 powder was heated to 1620 in a platinum crucible, ℃ and then the melted solid was cooled to 900 °C at a rate of 1°C/min. The whole process is carried out under a CO 2 The fundamental I-V characteristics of LuFe 2 O 4 were firstly measured on a number of polycrystalline materials that show up remarkable multiferroic in the charge ordered state as discussed in previous publications [1,5,6]. The current density (J) and electric field (E) in measurements were also computed numerically for each sample.…”

“…The charge ordering (CO) transtion at T c~5 10K in LuFe 2 O 4 is considered to be the origin of electric polarization for observed ferroelectricity [5]. Our , and the charge concentration has a nonsinusoidal charge density wave (CDW) characteristic [6]. Actually, the charge/spin frustrations in the ground state also play a critical role for the understanding of the magnetic order and the electronic ferroelectricity.…”