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A SiO 2 -Co film with a Pt bottom electrode and an Au top electrode was deposited by magnetron sputtering at room temperature. The sample exhibits bipolar resistive switching properties. Both oxygen vacancies and Co nanoparticles in the SiO 2 -Co film contribute to resistive switching properties and the formation of conducting filaments. The sample, at high and low resistance states, exhibits magnetoresistance at 300 K and 10 K, respectively; this may be due to spin-dependent tunneling between Co particles through the SiO 2 barriers. Thus, the combination of resistive switching and magnetoresistance in a simple Pt/SiO 2 -Co/Au structure leads to the formation of multiple resistance states, which is promising for future applications of multiple-state non-volatile storage.

Mg doped ZnO films with hexagonal wurtzite structure were deposited on c-cut sapphire Al2O3 substrates by pulsed laser deposition. Both room temperature ferromagnetism and band gap of the films simultaneously tuned by the concentration of oxygen vacancies were performed. Our results further reveal that the singly occupied oxygen vacancies should be responsible for the room temperature ferromagnetism and band gap narrowing. Singly occupied oxygen vacancies having the localized magnetic moments form bound magnetic polarons, which results in a long-range ferromagnetic ordering due to Mg doping. Moreover, band gap narrowing of the films is probably due to the formation of impurity band in the vicinity of valence band, originating from singly occupied oxygen vacancies. These results may build a bridge to understand the relationship between the magnetic and optical properties in oxide semiconductor, and are promising to integrate multiple functions in one system.

We demonstrate the synthesis of Fe 1−x Cr x Te 2 (0≤x≤0.6) nanoparticles by high-temperature organic-solution-phase method. The microstructure and magnetic properties were investigated by X-ray diffraction, transmission electron microscope and vibrating sample magnetometer. Cr doping can effectively improve the magnetic properties and morphology of FeTe 2 . Compared with the undoped FeTe 2 , Fe 1−x Cr x Te 2 spherical nanoparticles exhibit fine grain size of about 5 nm and uniform distribution. An ultrahigh room-temperature saturation magnetization of 7.34 emu/g can be obtained for Fe 0.85 Cr 0.15 Te 2 . It is 20 times higher than that of pure FeTe 2 . The lattice expansion caused by Cr doping is favorable for the enhancement of Fe–Fe and Fe–Cr ferromagnetic interaction in Fe 1−x Cr x Te 2 . Cr doping may be an effective approach to improve the magnetic properties of the other transition-metal chalcogenides.

Co/ZnO:Al granular films were made on glass substrates by sequential magnetron sputter deposition of ultrathin Co layer and ZnO:Al layer at room temperature. The as-deposited films consist of superparamagnetic Co particles dispersed in ZnO:Al (~2% Al) semiconductor matrix. Distinguished magnetoresistance effect at room temperature was obtained in the as-deposited films, which obviously reduced after annealing due to the growth of Co particles. The size of important magnetic particles was analyzed by Langevin function for hysteresis loops and magnetoresistance curves at room temperature. It was found that small magnetic particle contribute to magnetoresistance behavior and large particles dominate the room temperature magnetism in Co/ZnO:Al granular films.

Ionic liquid gating has emerged as an attractive means of manipulating the magnetic properties of materials. Here, we report ionic liquid gating modulating the ferromagnetism of a Co film. A weak and strong saturation magnetization can be reversibly obtained by applying a negative voltage and a positive one, respectively. The modulation may be related with the oxidization and reduction of Co. Negative (or positive) gating voltages drive the oxygen ions to inject into (or extract from) Co layer of the sample, which oxidizes (or reduces) Co. These gating processes are reversible. Moreover, the magnetism of the gated states is considerably stable. It is a significant step towards designing low-power electric-controlling magnetic devices in future.

Tunneling anisotropic magnetoresistance (TAMR) in the magnetic tunnel junctions (MTJs) driven by spin–orbit coupling (SOC) has attracted much attention for potential spintronic applications based on magnetic manipulation of electric transport. However, it has been believed that heavy metals are indispensable for the large TAMR. Here we experimentally show a TAMR of up to 46% in a La0.7Sr0.3MnO3 (LSMO) based MTJ without heavy metals. This value represents the largest TAMR for MTJs with half-metallic electrodes. We demonstrate that the TAMR ratio is enhanced by over one order of magnitude by tuning interface termination layer, achieving quasilocalized states at the interface Fermi level on the basis of magnetization orientation. These results are also supported by our first-principles density functional calculations. This finding illustrates a crucial role of interface tuning in the TAMR effect, opening a route for engineering the large anisotropic magnetoresistance by interface termination control and manipulating high spin polarization without using heavy metals.

The interfacial Dyzaloshinskii-Moriya interaction (DMI) plays a crucial role in stabilizing a chiral Neel-type magnetic domain wall in perpendicularly magnetized multilayers. In this work, we investigate the effect of oxide layers on interfacial DMI in ultrathin Pt/Co/SmOx and Pt/Co/AlOx stacks with the perpendicular magnetic anisotropy. The DMI effective field was characterized using the field driven domain wall creep and current-induced hysteresis loop shift methods. The experimental results show that an enhanced interfacial DMI is obtained in Pt/Co/SmOx stacks, which may be related to the oxidation degrees of the Co layer in view of the difference of Co/metallic oxide interfaces. Moreover, the X-ray photoelectron spectroscopy with the argon ion etching technique was used to further verify the weaker oxidation of the Co layer existed in Pt/Co/SmOx than that in Pt/Co/AlOx in the same annealing process due to the smaller electronegativity of the Sm compared to the Al element. Our results provide a promising route to effectively manipulate the interfacial DMI in spin-orbit-torque-based spintronic devices through the element electronegativity.

In this paper, the existence and global exponential stability of equilibrium point for inertial BAM neural networks with time delays are discussed. Firstly, by using homeomorphism theory and inequality technique, the LMI-based sufficient condition on the existence and uniqueness of equilibrium point for above inertial BAM neural networks is obtained. Secondly, a LMI-based condition which can ensure the global exponential stability of equilibrium point for the system is obtained by using LMI method and inequality technique. In our results, the boundedness assumption on the activation functions in Ke and Miao (2013) [19] , [20] is removed. Hence, our result on global exponential stability of equilibrium point for above system is less conservative.

In this paper, global exponential stability of inertial Cohen–Grossberg neural networks with time delays is investigated. By using Homeomorphism theorem and inequality technique, a LMI-based global exponential stability condition and inequality form global exponential stability condition are obtained for the above neural networks. In our result, the assumptions for the differentiability and monotonicity on the behaved functions in Ke and Miao (2013) [23] are removed. Thus our results are less conservative than those obtained in Ke and Miao (2013) [23] . Hence, we obtain new global exponential stability for this neural network.

In this paper, under the assumption that the activation functions only satisfy global Lipschitz conditions, a novel LMI-based sufficient condition for global asymptotic stability of equilibrium point of a class of BAM neural networks with reaction–diffusion terms and distributed delays is obtained by using degree theory, LMI method, inequalities technique and constructing Lyapunov functionals. In our results, the assumptions for boundedness and monotonicity in existing papers on the activation functions are removed.

In this work, we report the resistance switching behavior and its modulating magnetic properties and magnetoresistance of an Au/ZnO-Co/SiO2-Co/Pt structure. The ZnO-Co/SiO2-Co bilayers prepared by magnetron sputtering at room temperature contain Co nanoparticles embedded in the oxide matrices. Repeatable bipolar resistance switching is observed in the Au/ZnO-Co/SiO2-Co/Pt structure, accompanied with a change of magnetization and magnetoresistance. At high/low resistance state, the sample exhibits weak/strong saturation magnetization and large/small magnetoresistance ratio. The accumulation of oxygen vacancies and the appearance of oxygen-deficient ZnO1-x, more Co atoms and Zn atoms in the switching areas due to the motion of oxygen ions under electric stimuli may be counted for the occurrence of the resistive switching effect. During the processes, the variations of the number of oxygen vacancies and Co atoms offer the opportunity to modulate magnetoresistance and ferromagnetism of the sample. This work shows that the resistance, magnetoresistance and magnetic properties of the Au/ZnO-Co/SiO2-Co/Pt structure can be electrically tuned, which may supply clues for designing multifunctional devices.

We have grown room temperature ferromagnetic Fe, and Fe,Cu-codoped In 2 O 3 films on sapphire substrates by pulsed laser deposition. The magnetization of the Fe-doped In 2 O 3 films was independent of the thickness and the observed ferromagnetism was almost homogeneous. The addition of Cu caused the films to exhibit obvious thickness dependent magnetization and the ferromagnetism became inhomogeneous. The temperature dependence of the magnetization, X-ray absorption fine structure and magnetic circular dichroism data, clearly established the presence of Fe metal clusters in Fe,Cu-codoped In 2 O 3 films, which contribute to the inhomogeneous ferromagnetism.

The structural and magnetic properties of (Mn, Fe)-codoped ZnO powders as well as thin films were investigated. The X-ray diffraction and magnetic measurements indicated that the higher sintering temperature facilitates more Mn and Fe incorporation into ZnO. Magnetic measurements indicated that the powder sintered in air at 800 °C showed paramagnetic, but it exhibited obvious room temperature ferromagnetism after vacuum annealing at 600 °C. The results revealed that magnetic clusters were the major contributors to the observed ferromagnetism in vacuum-annealed Zn0.98Mn0.01Fe0.01O powder. Interestingly, the room temperature ferromagnetism was also observed in the Zn0.98Mn0.01Fe0.01O film deposited via pulsed laser deposition from the air-sintered paramagnetic target, but the secondary phases in the film were not detected from X-ray diffraction, transmission electron microscopy, and zero-field cooling and field cooling. Apparently, the magnetic natures of powders and films come from different origins.