Hyper-sensitive piezophotovoltaic effects in ferroelectric nanocylinders

Abstract

Photocurrent system of the ferroelectric nanocylinder ͑FNC͒, including nanodisks, nanorods, and nanowires, sandwiched between metal electrodes with the short-circuit boundary conditions has been designed and investigated. Taking into account the polarization charge screening in the electrodes and near-surface inhomogeneous polarization distribution, a theoretical model for investigating the photoinduced current of the FNC under the illumination of light was established. Our results show that the photocurrent of the FNC can be totally controlled by adjusting its size and states of the polarization "up" and "down." Especially, reversing an applied stress can obviously change the photocurrent of the FNC, which is particularly significant near the stress-dependent para/ferroelectric phase transition. This piezophotovoltaic effect may have good potential for applications in high-sensitivity photomechanical sensors, memories, switchable nanodevices, or other photovoltaic nanodevices.

New multiferroics based on EuxSr1−xTiO3 nanotubes and nanowires

“…The intrinsic surface stress can induce ferroelectricity, ferromagnetism and increase corresponding phase transition temperatures in conventional ferroelectrics and quantum paraelectric nanorods, nanowires [15,16,17,18,19] and binary oxides [20].The surface stress is inversely proportional to the surface curvature radius and directly proportional to the surface stress tensor (similar to Laplace surface tension). Thus, the intrinsic surface stress should depend both on the growth conditions and the surface termination morphology [21,22].…”

“…The continuum media theory was successfully used for the analysis of elastic properties of metallic, semiconductor, dielectric or polymeric nanowires and nanotubes [31,32,33,34,35,36,37] and the piezoelectric response [38]. For nanosized ferroics, the applicability of the continuous media phenomenological theory is corroborated by the fact that the critical sizes (~2-10 lattice constants) of the appearance of long-range order calculated from atomistic [ 39 , 40 ] and phenomenological theories [17,18,19] are in good agreement with each other [37,41,42,43,44] as well as with experimental results [45]. Generally, the long-range order appears for sizes larger than the critical sizes (details can be found in Refs.…”

“…Generally, the long-range order appears for sizes larger than the critical sizes (details can be found in Refs. [17][18][19][20]25]). Once the long-range order is established, it is possible to apply the mean field LGD theory [46].…”

Ferroelectricity and ferromagnetism in EuTiO3nanowires

“…It is shown that the intrinsic surface stress can induce ferroelectricity, ferromagnetism and increase corresponding phase transition temperatures in conventional and quantum paraelectric nanorods and nanowires [11,12,13,14,15]. These facts motivated us to explore the possibility of inducing simultaneous ferroelectricity and ferromagnetism in EuTiO 3…”

Surface and size effects on phase diagrams of ferroelectric nanocylinders

“…Under the absence of external electric field, the thermodynamic energy of a FNC should contain the contributions of the gradient, interface, surface, and depolarization field energies. [4][5][6][7][8][9][10][11][12][13][14][15] The gradient energy density is given by DG grad ¼ 1=2D ij P i;j P i;j , where D ij are the gradient coefficients and @P i =@x j are expressed by P i;j . 13,15 The top and bottom interface energy and sidewall surface energy approximately acquire the forms as…”