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Fe-based superconductors are one of the current research focuses. FeTe is unique in the series of FeSe1−x Te x , since it is nonsuperconducting near the FeTe side in the phase diagram in contrast to the presence of superconductivity in other region. However, FeTe thin films become superconducting after oxygen annealing and the mechanism remains elusive. Here, we report the temperature dependences of resistivity, Hall effect and magnetoresistance (MR) of a series of FeTe thin films with different amounts of excess Fe and oxygen. These properties show dramatic changes with excess Fe and oxygen incorporation. We found the Hall coefficients are positive for the oxygen-annealed samples, in contrast to the transition from positive to negative below 50 K for the vacuum-annealed samples. For all samples, both the resistivity and Hall coefficient show a dramatic drop, respectively, at around 50 K–75 K, implying coexistence of superconductivity and antiferromagnetic order for the oxygen-annealed samples. The vacuum-annealed samples show both positive and negative values of MR depending on temperature, while negative MR dominates for the oxygen-annealed samples. We also found that oxygen annealing reduces the excess Fe in FeTe, which has been neglected before. The results are discussed in terms of several contributions, and a comparison is made between the oxygen-annealed FeTe thin films and FeSe1−x Te x . This work is helpful for shedding light on the understanding of oxygen-annealed FeTe thin films.

The magnetic anisotropy manipulation in the Sm3Fe5O12 (SmIG) films and its effect on the interfacial spin coupling in the CoFe/SmIG heterostructures were studied carefully. By switching the orientation of the Gd3Ga5O12 substrates from (111) to (001), the magnetic anisotropy of obtained SmIG films shifts from in-plane to out-of-plane. Similar results can also be obtained in the films on Gd3Sc2Ga3O12 substrates, which identifies the universality of such orientation-induced magnetic anisotropy switching. Additionally, the interfacial spin coupling and magnetic anisotropy switching effect on the spin wave in CoFe/SmIG magnetic heterojunctions have also been explored by utilizing the time-resolved magneto–optical Kerr effect technique. It is intriguing to find that both the frequency and effective damping factor of spin precession in CoFe/SmIG heterojunctions can be manipulated by the magnetic anisotropy switching of SmIG films. These findings not only provide a route for the perpendicular magnetic anisotropy acquisition but also give a further path for spin manipulation in magnetic films and heterojunctions.

A tunable and nonvolatile magnetoelectric coupling effect and magnetization reversal in demagnetized Ta/CoFeB/(011)PMN-PT was obtained by applying electric fields without an external magnetic field. The XMCD investigation under in situ electric field indicates that the orbital magnetic moment to spin magnetic moment ratios of both Fe and Co are enhanced under electric field. The ratio of Fe under negative electric field control is much larger than it under positive electric field, while it remains almost unchanged for Co under different electric fields.

C-axis vertically aligned ZnO nanorod arrays were synthesized on a ZnO thin film through a simple hydrothermal route. The nanorods have a diameter of 30–100 nm and a length of about several hundred nanometres. The gas sensor fabricated from ZnO nanorod arrays showed a high sensitivity to H2 from room temperature to a maximum sensitivity at 250 °C and a detection limit of 20 ppm. In addition, the ZnO gas sensor also exhibited excellent responses to NH3 and CO exposure. Our results demonstrate that the hydrothermally grown vertically aligned ZnO nanorod arrays are very promising for the fabrication of cost effective and high performance gas sensors.

SnO2 thin films were deposited by RF inductively coupled plasma enhanced chemical vapour deposition and then the as-deposited SnO2 thin films were immersed in the plasma for plasma post-treatment. Uniform SnO2 nanorods were grown in situ from the SnO2 thin films during plasma treatment and formed a hybrid structure of SnO2 nanorod thin films consisting of one-dimensional SnO2 nanorods embedded in the two-dimensional SnO2 thin film matrix. The growth of SnO2 nanorods follows a sputtering redeposition mechanism. Due to the intrinsically small grain size and high surface-to-volume ratios associated with the nanorods, the SnO2 nanorod thin films showed much higher sensitivity at lower operating temperatures together with faster response and shorter recovery time compared with the as-deposited SnO2 thin films.

SnO2 thin films have been deposited by radio-frequency inductively coupled plasma-enhanced chemical vapour deposition using dibutyltin diacetate as the precursor. The as-deposited SnO2 thin films were post-treated in the inductively coupled plasma. After plasma treatment, uniform SnO2 nanorods were grown on the SnO2 thin films. The nanorods were formed by a sputtering–redeposition mechanism. The effects of the conditions of the plasma treatment on the morphology of plasma-treated SnO2 thin films were studied. The plasma power and the gaseous composition of the plasma had a great effect on the growth of SnO2 nanorods from SnO2 thin films. The type of plasma was also very critical, and no nanorods were grown on the SnO2 thin films treated in capacitively coupled plasma.

The failure of a silver nanowire (AgNW) random network due to high electric current density is described. The AgNW network breaks down as result of electromigration and Joule heating at junctions, which leads to destroyed interconnections between AgNWs. The AgNW network is not completely destroyed after breakdown, but instead is able to undergo multiple breakdowns after being cooled down, with increased resistance and reduced breakdown current density. The breakdown current density of AgNW network is J(max) = 25 A cm(-2) for a network with R(s) ~ 40 Ω sq(-1) outperforming a CuNW network. An effective electrical annealing method is demonstrated to decrease network resistance by 18% by periodically applying high current that is slightly lower than breakdown current with a period of 1 min for a few cycles.

High-quality single-crystalline thin films of n = 5 (n denotes the period of the Aurivillius structure) multiferroic Aurivillius oxides were obtained by determining and applying an optimal growth temperature of 605 °C and oxygen pressure of 20 Pa using pulsed laser deposition. The optimal growth ranges were narrower than 30 °C for the temperature and 10 Pa for the pressure. The optimized thin films exhibited obvious ferroelectric polarization switching in the out-of-plane direction as well as weak ferromagnetism with a saturation magnetization of less than 10 emu/cm3.

Electric-field control of non-volatile magnetization switching in the absence of external-magnetic-field bias has been investigated in multiferroic Co40Fe40B20/0.7Pb(Mg1/3Nb2/3)-0.3PbTiO3 (CoFeB/PMN-0.3PT) heterostructure at room temperature. The two non-volatile magnetic states are achieved without magnetic-field bias and can be switched in a reversible and reproducible manner by an electric field. These results are attributed to the modulation of the magnetic anisotropy of the CoFeB layer by as-grown magnetic field and electric-field?induced non-volatile strain through unipolar-electric-field cycling. High-resolution X-ray diffraction studies on the (022) peaks under in situ electric field indicate that the non-volatile strain is closely related to the 71? ferroelastic domain switching ( to ) of the PMN-0.3PT substrate. The corresponding ratio of the ferroelastic domain is electrically changed by 14.1% between the two non-volatile magnetic states. Our results provide a promising path to non-magnetically operating magnetic bits by pure electric field at room temperature.

Multiwalled carbon nanotubes (MWCNT) were homogeneously covered with a bio-functional polydopamine (PDOP) by a simple dip-coating approach in mild basic solution. Then, uniformly dispersed and highly loaded platinum nanoparticles (PtNPs) were deposited on MWCNT@PDOP by a mild reductant, and were characterized by transmission electron microscopy and x-ray photoelectron spectroscopy. Afterwards, this nanocomposite was modified on the glass carbon electrode and applied to simultaneously determine dopamine (DA) and uric acid (UA) by differential pulse voltammetry (DPV). Results showed that a linear electro-oxidation response was found for DA and UA in the range of 0.25-20 μM and 0.3-13 μM with the detection limit (S/N = 3) of 0.08 μM and 0.12 μM, respectively. In addition, the detection sensitivities for DA and UA by DPV were 1.03 μA μM(-1) and 2.09 μA μM(-1), respectively, which were much higher than those from a cyclic voltammogram. Finally, the reproducibility and stability of the nanocomposite were also evaluated, demonstrating that such MWCNT@PDOP@PtNPs can be a promising candidate for advanced electrode material in electrochemical sensing and other electrocatalytic applications.