Ferroelectricity in Si-doped HfO2 Revealed: A Binary Lead-free Ferroelectric

Static domain structures and polarization dynamics of silicon doped HfO2 are explored. The evolution of ferroelectricity as a function of Si-doping level driving the transition from paraelectricity via ferroelectricity to antiferroelectricity is investigated. Ferroelectric and antiferroelectric properties can be observed locally on the pristine, poled and electroded surfaces, providing conclusive evidence to intrinsic ferroic behavior.

Neural basis of language switching in the brain: fMRI evidence from Korean-Chinese early bilinguals

Using fMRI, we conducted two types of property generation task that involved language switching, with early bilingual speakers of Korean and Chinese. The first is a more conventional task in which a single language (L1 or L2) was used within each trial, but switched randomly from trial to trial. The other consists of a novel experimental design where language switching happens within each trial, alternating in the direction of the L1/L2 translation required. Our findings support a recently introduced cognitive model, the 'hodological' view of language switching proposed by Moritz-Gasser and Duffau. The nodes of a distributed neural network that this model proposes are consistent with the informative regions that we extracted in this study, using both GLM methods and Multivariate Pattern Analyses: the supplementary motor area, caudate, supramarginal gyrus and fusiform gyrus and other cortical areas. 

A diode for ferroelectric domain-wall motion

For over a decade, controlling domain wall injection, motion and annihilation along nanowires has been the preserve of the nanomagnetics research community. Revolutionary technologies have resulted, like race-track memory and domain wall logic. Until recently, equivalent research in analogous ferroic materials did not seem important. However, with the discovery of sheet conduction, the control of domain walls in ferroelectrics has become vital for the future of what has been termed “domain wall electronics”. Here we report the creation of a ferroelectric domain wall diode, which allows a single direction of motion for all domain walls, irrespective of their polarity, under a series of alternating electric field pulses. The diode’s saw-tooth morphology is central to its function. Domain walls can move readily in the direction in which thickness increases gradually, but are prevented from moving in the other direction by the sudden thickness increase at the saw-tooth edge.

Epitaxial growth of non-c-oriented ferroelectric SrBi2Ta2O9 thin films on Si(100) substrates

Epitaxial SrBi2Ta2O9 (SBT) thin films with well-defined (116) orientation have been grown by pulsed laser deposition on Si(100) substrates covered with an yttria-stabilized ZrO2 (YSZ) buffer layer and an epitaxial layer of electrically conductive SrRuO3. Studies on the in-plane crystallographic relations between SrRuO3 and YSZ revealed a rectangle-on-cube epitaxy with respect to the substrate. X-ray diffraction pole figure measurements revealed well defined orientation relations, viz. SBT(116)\\ SrRuO3(110)\\ YSZ(100)\\ Si(100), SBT[110]\\ SrRuO3[001], and SrRuO3[111]\\ YSZ[110]\\ Si[110].

Switching ‘on’ the Luminescence of One Metal Ion with Another: Selectivity Characteristics with Respect to the Emitting and Triggering Metal

Complexes 1a·EuIII and 1b·EuIII, but not 1a·TbIII and 1b·TbIII, display strong ‘off–on’ switching of delayed luminescence with alkali cations; the switching efficiency of 1b·EuIII is stronger with K+ rather than Na+.

Starting slow: the effects of response-switching frequency on patterns of cardiovascular reactivity

Research findings suggest that switching between competing response sets can be resource demanding. The current study focused on concurrent health-relevant physiological effects of task switching by assessing cardiovascular response at varying levels of switch frequency. The participants performed a response-switching task at three different levels of response set switching frequency (low, medium and high) while measurements of blood pressure and heart rate were taken. One group was exposed to response-switching frequency conditions in the order low → medium → high, while the other group was exposed to the same task conditions in the reverse order (i.e. high → medium → low). The results showed that the participants in the low → medium → high switch frequency group recovered faster from initially heightened systolic blood pressure when compared with participants in the high → medium → low group. It is concluded that the results point to a physiological "carry over" effect associated with beginning a task at rapid response switching frequency levels, and suggest the importance of habituation to task demands as a means of offsetting potentially unhealthy levels of reactivity. Implications for modern work environments are discussed.

Ferroelectric Vortices and Related Configurations

This chapter discusses that the theoretical studies, using both atomistic and phenomenological approaches, have made clear predictions about the existence and behaviour of ferroelectric (FE) vortices. Effective Hamiltonians can be implemented within both Monte Carlo (MC) and molecular dynamics (MD) simulations. In contrast to the effective Hamiltonian method, which is atomistic in nature, the phase field method employs a continuum approach, in which the polarization field is the order parameter. Properties of FE nanostructures are largely governed by the existence of a depolarization field, which is much stronger than the demagnetization field in magnetic nanosystems. The topological patterns seen in rare earth manganites are often referred to as vortices and yet this claim never seems to be explicitly justified. By inspection, the form of a vortex structure is such that there is a continuous rotation in the orientation of dipole vectors around the singularity at the centre of the vortex.