We report a large and nonvolatile bipolar-electric-field-controlled magnetization at room temperature in a Co(40)Fe(40)B(20)/Pb(Mg(1/3)Nb(2/3))(0.7)Ti(0.3)O(3) structure, which exhibits an electric-field-controlled looplike magnetization. Investigations on the ferroelectric domains and crystal structures with in situ electric fields reveal that the effect is related to the combined action of 109° ferroelastic domain switching and the absence of magnetocrystalline anisotropy in Co(40)Fe(40)B(20). This work provides a route to realize large and nonvolatile magnetoelectric coupling at room temperature and is significant for applications.

We report a giant electric-field control of magnetization (M) as well as magnetic anisotropy in a Co40Fe40B20(CoFeB)/Pb(Mg1/3Nb2/3)0.7Ti0.3O3(PMN-PT) structure at room temperature, in which a maximum relative magnetization change (ΔM/M) up to 83% with a 90° rotation of the easy axis under electric fields were observed by different magnetic measurement systems with in-situ electric fields. The mechanism for this giant magnetoelectric (ME) coupling can be understood as the combination of the ultra-high value of anisotropic in-plane piezoelectric coefficients of (011)-cut PMN-PT due to ferroelectric polarization reorientation and the perfect soft ferromagnetism without magnetocrystalline anisotropy of CoFeB film. Besides the giant electric-field control of magnetization and magnetic anisotropy, this work has also demonstrated the feasibility of reversible and deterministic magnetization reversal controlled by pulsed electric fields with the assistance of a weak magnetic field, which is important for realizing strain-mediated magnetoelectric random access memories.

Liquid-crystalline blue phases (BPs) have sparked an enormous interest due to their exotic optical properties, exhibiting no birefringence but selective refl ection of circularly polarized light, and potential for advanced applications in a wide variety of fi elds including self-assembling tunable photonic crystals and fast-response display. [ 1 ] BPs are made up of double-twist cylinders arranged in a highly fl uid self-assembled cubic lattice with periods of ∼ 100 nm, which is stabilized by a network of topological -1/2 disclination lines. The competition between the chiral forces and the packing topology leads to at least three different lattice structures, labeled as blue phase III (BPIII), blue phase II (BPII), and blue phase I (BPI) upon decreasing the temperature from the isotropic (I) to the chiral nematic phase. [ 2 ] The packing structures are macroscopically amorphous, simple cubic, and body-centered cubic, respectively. [ 3 ] As is known, the main obstacles to the potential applications of the BPs are the narrow temperature range as well as the instability of cubic structure against an electric fi eld. [ 4 ] Recent developments that introduce BPs with an extended temperature range [ 5 ] make them more attractive for applications. However, the stability of cubic structures against an electric fi eld, such as heavy hysteresis or irreversible switching, is still a big challenge on the road toward practical applications.Theoretical investigations of the BP switching dynamics in presence of an electric fi eld have shown that cubic structure (especially, BPI) is unstable and diffi cult to be reversibly switched in the strong fi eld region. [ 6 ] It has been experimentally demonstrated that serious hysteresis was observed in the pure BPs, which may be due to the fi eld induced phase transition from BP to a chiral nematic phase. [ 7 ] Interestingly, polymer-stabilized BPs (PSBP) could be reversibly switched with microsecond response time, [ 5 ] but the driving voltage of these system is relatively high due to the doping of ∼ 10.0 wt% monomers, and the long-term stability of polymer network is a remaining technical challenge. [ 1 , 8 ] Moreover, BPIII could also undergo a reversible switching with an AC fi eld of less than 10.0 V μ m − 1 but the response speed is relatively slow (about several millisecond) due to the fact that BPIII with wide temperature range is usually observed in the systems with high chirality or viscosity. [ 9 ] Therefore, there is an urgent need to explore a novel strategy to solve the instability of cubic BPs against an electric fi eld and develop the BP composites without hysteresis, with fast response speed, and with low driving voltage.Liquid-crystal nanoscience has attracted special attention in recent years due to the potential applications in developing new composite materials with exciting optical as well as electro-optical properties. [ 10 ] Doping nematic liquid crystals (LC) with nanoparticles (NPs) has lead to many promising LC electro-optical characteristics including low ...

Electro-optical switching with low voltage, free hysteresis and fast response speed is achieved in a facile manner by dispersing a small amount of ferroelectric nanoparticles (NPs) into blue phase liquid crystal. The large dipole moment of NPs contributes to the hysteresis-free switching, whereas the low voltage operation results from the introduction of the ferroelectric properties inherent to the NPs.Blue phase (BP) liquid crystal display (LCD) devices based on the optical Kerr effect are emerging as some of the leading candidates for the next-generation display technology because they exhibit the following revolutionary features: 1 (1) submillisecond gray-to-gray response time that enables field sequential display without using color filters, (2) no need for a surface alignment layer which greatly simplifies the fabrication process, (3) wide and symmetric viewing angle, and (4) cell-gap insensitivity provided that an in-planeswitching (IPS) electrode is employed. Recent developments that introduce BPs with an extended temperature range 2 make them more attractive for applications in LCDs, and Samsung Co. demonstrated the first BP LCD prototype based on polymer stabilized BPs (PSBP) in 2008. 3 However, some bottlenecks such as voltage-induced serious hysteresis and high driving voltage, still remain to be overcome before widespread applications of BP LCD can take off. The hysteresis-free BPLC has been previously achieved by introducing the polymers with flexible chains or the inorganic NPs with large dipole moment, 2d,4 but the high driving voltage (>50.0 V) is a big challenge on the road toward practical applications. Therefore, there is an urgent need to explore a novel strategy to reduce the driving voltage and develop the BP composites with low driving voltage and free hysteresis.It has already been theoretically predicted that the driving voltage (on-state voltage, V on ) is closely related to the Kerr constant of materials and the electrode configuration of devices, and a large Kerr constant or a uniform electric field which penetrates deeply into the bulk liquid crystal (LC) layer helps to reduce the driving voltage of BP LCD. 5 Extensive work on developing new BPLC materials and low-voltage device structures has been recently performed. On the one hand, to enlarge the Kerr constant, the materials with large intrinsic birefringence and dielectric anisotropy have been prepared by the conventional time-consuming and expensive chemically synthetic methods, 6 whereas enhancing the Kerr constant by increasing the Dn$D3 of host LCs unavoidably leads to increased viscosity, which in turn lengthens the response time. On the other hand, to optimize the device structures, several new electrode configurations, such as protrusion electrode, 7 wall-shaped electrode, 8 corrugated electrode 9 and vertical field switching (VFS) electrode, 10 have been proposed one after the other. Despite their remarkable achievements in reducing the driving voltage, many other problems such as sophisticated device fabrication, noticeab...

The preference for the chromaticity of high illuminance, high colour rendering LED illumination of different scenes was investigated for Chinese and European observers. An experiment about the preference for perceived illumination chromaticity was conducted with the same multi-LED light engine, same viewing booth and same coloured objects transported between Germany and China. Observer preference for perceived illumination chromaticity was significantly influenced by correlated colour temperature (2700 K–6500 K), object scene colour (red, blue or mixed), cultural background (Chinese or European origin, living in Germany or in China) and gender (men, women). The results can be used to choose an appropriate correlated colour temperature (e.g. warm white or cool white) for a high-quality lighting product to illuminate different object scenes (e.g. red or blue objects) so as to achieve good user acceptance in the global market.

No abstract

Thiophene-based bent-shaped mesogens were firstly applied to extend the blue phase range. And the electro-optical performances of liquid crystalline composites doped with different concentration of these bent-shaped mesogens were also explored by incorporating in-plane electric field geometry.

The in vivo monitoring of ascorbic acid (AA) following physiological and pathological events is of great importance because AA plays a critical role in brain functions. The conventional electrochemical sensors (ECSs) usually suffered from poor selectivity and sluggish electron transfer kinetics for cerebral AA oxidation. The exploitation of ECSs adapt to the electrochemical detection (ECD)–microdialysis system, here we reported a facile ratiometric electrochemical sensor (RECS) for in vivo/online repetitive measurements of cerebral AA in brain microdiaysate. The sensor were constructed by careful electrodeposition of graphene oxide (GO) onto glassy carbon (GC) electrodes. Methylene blue (MB) was electrostatically adsorbed onto the GO surface as a built-in reference to achieve ratiometric detection of AA. The subsequent proper electroreduction treatment was able to readily facilitate the oxidation of AA at a relatively negative potential (−100 mV) and the oxidation of MB at separated potential (−428 mV). The in vitro experiments demonstrated that the RECS exhibited high sensitivity (detection limit: 10 nM), selectivity, and stability toward AA determination, enabling the in vivo/online repetitive measurement of cerebral AA in brain microdiaysate with high reliability. As a result, the designed RECS was successfully applied in the ECD–microdialysis system to in vivo/online repetitive monitoring the dynamic change of cerebral AA in the progress of the global cerebral ischemia/reperfusion events. More, the microinjection of endogenous AA and AA oxidase (AAOx) verified the reliability of the proposed RECS for in vivo/online repetitive cerebral AA detection. This proposed sensor filled the gap that no rational electrochemical sensor has been developed for the ECD–microdialysis system since its creation by the Mao group in 2005, which provided a reliable and effective method for brain chemistry research.