The toroidal order of electric dipoles in ferroelectric materials has attracted attention in the past decade due to fascinating properties and great potential for enabling novel memory devices,and functional devices in general.However,facile manipulation of toroidal order in ferroelectrics remains challenging.Here,using first-principles derived simulations,we demonstrate an efficient scheme to control the polar-toroidal multi-order(PTMO)states in ferroelectric nanowires.Two feasible strategies of controlling PTMO states by a combination of homogeneous electric field and torque are carried out in ferroelectric/paraelectric composite nanowires.This is possible based on trilinear coupling between polarization,toroidization and the twist force.As a result,switching of the toroidization of the nanowire can be readily achieved by reversal of the axial polarization.The torque threshold needed to control PTMO states is also calculated and found to be relatively small,indicating the feasibility of this method.Our study demonstrates facile control of PTMO states,including ferroelectric skyrmions,in ferroelectrics and is a step towards designing ferroelectric devices based on multi-order states.
In this paper,we introduce our finding of the effects of C_(60) nanoparticles (NP) infiltration on mechanical properties of cell and its membrane.Atomic force microscopy (AFM) is used to perform indentation on both normal and C_(60) infiltrated red blood cells (RBC) to gain data of mechanical characteristics of the membrane.Our results show that the mechanical properties of human RBC membrane seem to be altered due to the presence of C_(60) NPs.The resistance and ultimate strength of the C_(60) infiltrated RBC membrane significantly decrease.We also explain the mechanism of how C_(60) NPs infiltration changes the mechanical properties of the cell membrane by predicting the structural change of the lipid bilayer caused by the C_(60) infiltration at molecular level and analyze the interactions among molecules in the lipid bilayer.The potential hazards and application of the change in mechanical characteristics of the RBCs membrane are also discussed.Nanotoxicity of C_(60) NPs may be significant for some biological cells.
Nanoscale PbxLa1-,Ti1-x/4O3 （PLT） thin film has been fabricated on Pt／Ti／SiO2／Si substrates by chemical solution deposition （CSD） method. Ferroelectricity of the fresh-made PLT thin film has been clearly detected through piezoelectric force microscopy （PFM） by writing reversible ferroelectric domains. However, PLT thin film also shows off-standard ferroelectric hysteresis loops highly dependent on frequency, indicating large amount of mobile space charges in the film. Subsequent current-voltage （C-V） studies show that sandwich-like Pt／PLT／Pt structure exhibits notable bipolar resistive switching （BRS） characteristics with high stability （〉 103 switching cycles）. It is found that the C-V curves of both high- and low-resistance states have the feature of space-charge-limited current （SCLC） conduction, indicating important roles of defects in the conduction. X-ray photoelectron spectroscopy measurement further verifies that oxygen vacancies based conductive filament mechanism is likely responsible for the observed RS effect. Our demonstration of stable RS effect in the PLT thin film and its possible coupling with ferroelectricity is promising in device development and applications, such as development of ferroelectric-tunable RS memories.
