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Biological neuronal networks are the computing engines of the mammalian brain. These networks exhibit structural characteristics such as hierarchical architectures, small-world attributes, and scale-free topologies, providing the basis for the emergence of rich temporal characteristics such as scale-free dynamics and long-range temporal correlations. Devices that have both the topological and the temporal features of a neuronal network would be a significant step toward constructing a neuromorphic system that can emulate the computational ability and energy efficiency of the human brain. Here we use numerical simulations to show that percolating networks of nanoparticles exhibit structural properties that are reminiscent of biological neuronal networks, and then show experimentally that stimulation of percolating networks by an external voltage stimulus produces temporal dynamics that are self-similar, follow power-law scaling, and exhibit long-range temporal correlations. These results are expected to have important implications for the development of neuromorphic devices, especially for those based on the concept of reservoir computing.

Magnetic sensors are key elements in many industrial, security, military, and biomedical applications. Heusler alloys are promising materials for magnetic sensor applications due to their high spin polarization and tunable magnetic properties. The dynamic field range of magnetic sensors is strongly related to the perpendicular magnetic anisotropy (PMA). By tuning the PMA, it is possible to modify the sensing direction, sensitivity and even the accuracy of the magnetic sensors. Here, we report the tuning of PMA in a Co2MnGa Heusler alloy film via argon (Ar) ion irradiation. MgO/Co2MnGa/Pd films with an initial PMA were irradiated with 30 keV 40Ar+ ions with fluences (ions·cm−2) between 1 × 1013 and 1 × 1015 Ar·cm−2, which corresponds to displacement per atom values between 0.17 and 17, estimated from Monte-Carlo-based simulations. The magneto optical and magnetization results showed that the effective anisotropy energy (Keff) decreased from ~153 kJ·m−3 for the un-irradiated film to ~14 kJ·m−3 for the 1 × 1014 Ar·cm−2 irradiated film. The reduced Keff and PMA are attributed to ion-irradiation-induced interface intermixing that decreased the interfacial anisotropy. These results demonstrate that ion irradiation is a promising technique for shaping the PMA of Co2MnGa Heusler alloy for magnetic sensor applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Rb-doped BNT–BT films were grown on Pt substrate by metal organic solution deposition technique. [•] All Rb-doped BNT–BT films have a single phase perovskite structure with no secondary phase. [•] Optimal electrical properties were obtained for 5mol% Rb doped BNT–BT films. [Copyright &y& Elsevier]

Highlights: [•] Lead-free Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3–BaTiO3 piezoelectric thin films with compositions near morphotropic phase boundary were grown on Pt/Ti/SiO2/Si (100) substrates using metal-organic solution method. [•] All BNT–BKT–BT films have a single phase perovskite structure with no pyrochlore phases. [•] 0.884BNT–0.036BT–0.08BKT thin film (n =2) has the best surface morphology compared with other films. [ABSTRACT FROM AUTHOR]

Abstract: Lead-free 0.94Bi0.5Na0.5TiO3–0.06BaTiO3 (BNT–BT) piezoelectric thin films were prepared by metal-organic solution deposition onto a Pt/Ti/SiO2/Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700°C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200nm. Thin films of 356nm thickness exhibited a small signal dielectric constant and a loss tangent at 1kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5μC/cm2 with a coercive field of 164.5kV/cm. The leakage current density of the thin film was 4.08×10−4 A/cm2 at an applied electric field of 200kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d 33) of the BNT–BT thin film was approximately 51.6pm/V. [Copyright &y& Elsevier]

Abstract: Tantalum (Ta5+) doped CaCu3Ti4−x Ta x O12 (x =0.05 and 0.10) ceramics were prepared by semi-wet route using solid Ta2O5 powder and metal nitrate solutions. Powder X-ray diffraction confirmed the major phase formation of cubic CaCu3Ti4O12 ceramic in the doped samples sintered at 900°C for 6h. Microstructure has been studied using field-emission scanning electron microscopy. The grain size is in the range of 150nm to 1μm for both compositions. Dielectric constant of the samples increases with increasing tantalum concentrations. [Copyright &y& Elsevier]