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The micro-discharge effect limits the development of high-frequency microwave power components to miniaturization and integration. Therefore, it has become a focus of research to effectively suppress the micro-discharge effect, increase the micro-discharge threshold, and strengthen the environmental stability of high-frequency microwave devices. In this study, different elemental ratios of carbon (C)/silver (Ag)/titanium (Ti) composite films were obtained by multi-target magnetron co-sputtering technology and then systematically analyzed for micro-discharge effects. When the doping ratio of C/Ag/Ti was 3.538/1/0.013, the corresponding maximum secondary electron emission coefficient (δmax) decreased to 1.01 owing to the suppression of secondary electron emission by the increase in the content of sp2 hybrid bond. The micro-discharge threshold of Ku band waveguide filters coated with moderate C/Ag/Ti composite films showed an optimal performance of 10 000−12 500 W, which was increased by approximately 20 times. Moreover, the microstructure of the composite films exhibited higher density and flatness with a tiny increase in the titanium doping ratio, representing good environmental stability. Thus, the effective suppression of the secondary electron emission yield, significant improvement in the micro-discharge threshold, and enhancement of the environment stability of microwave components could be realized simultaneously by reasonably controlling the content of titanium in silver and titanium co-doped carbon-based composite films. [ABSTRACT FROM AUTHOR]

The ever-increasing demand for larger surface area, well-defined, and conformal multi-layer nanostructures in gas sensor, catalyst and solar cell applications has propelled the exploration of such nanostructures within an atomic resolution. The atomic layer deposition (ALD) technique is ideal for the synthesis of these nanostructures due to its excellent step coverage ability on high aspect ratio nanostructures. In this work, different coaxial nanotube networks are successfully fabricated by electrospinning and ALD, with a well-controlled phase. We systematically studied the temperature-induced microstructures and photoluminescence property evolution of the nanotube network. The Al2O3/ZnO/Al2O3 tri-layer nanotube network is obtained by sintering at 400 °C, and a ZnAl2O4 core-shell nanotube structure has formed by the Kirkendall effect by further post-annealing at 700 °C. Oxygen accumulation is clearly observed at the small neck feature, but the Zn and Al elements are uniformly distributed along the whole nanotube. Photoluminescence emission obtained in this work is so broad that it almost covers the whole visible light wavelength range. The results indicate that the microstructures and photoluminescence properties can be well-controlled by the post-annealing temperature. It provides an available platform for realizing conformal 3D nano-devices. [ABSTRACT FROM AUTHOR]

The steady motion of magnetic domain wall driven by spin-orbit torques is investigated analytically in the heavy/ferromagnetic metal nanowires for three cases with a current transverse to the in-plane and perpendicular easy axis, and along the in-plane easy axis. By the stability analysis of Walker wall profile, we find that if including the higher-order spin-orbit torques, the Walker breakdown can be avoided in some parameter regions of spin-orbit torques with a current transverse to or along the in-plane easy axis. However, in the case of perpendicular anisotropy, even considering the higher-order spin-orbit torques, the velocity of domain wall cannot be efficiently enhanced by the current. Furthermore, the direction of wall motion is dependent on the configuration and chirality of domain wall with a current along the in-plane easy axis or transverse to the perpendicular one. Especially, the direction of motion can be controlled by the initial chirality of domain wall. So, if only involving the spin-orbit mechanism, it is preferable to adopt the scheme of a current along the in-plane easy axis for enhancing the velocity and controlling the direction of domain wall. [ABSTRACT FROM AUTHOR]

A theoretic study is presented on the magnetization dynamics in magnetic multilayers with two tilted spin polarizers. Magnetic phase diagrams are established under the control of the magnitude and direction of dual spin torques. Different magnetic states, including parallel and antiparallel orientations, out-of-plane orientations, in-plane, and out-of-plane precessions, bistable states, can be distinguished in the phase diagrams. For the bistable states, there exists hysteretic switching between static and dynamic states. Selecting different pinned-layer configurations, the reversal between parallel and antiparallel orientation and the switching from stable states to precessional ones can be realized by increasing current. In addition, the dynamic evolutions of magnetic states are demonstrated. [ABSTRACT FROM AUTHOR]

We theoretically investigate the current-excited and adjusted ferromagnetic resonance in magnetic trilayers with a tilted spin polarizer. The current- and frequency-swept resonant spectra are obtained by the linearization method. We find that the precessional frequency, the equilibrium position, the energy pumping and damping, and the resonant linewidth and location can be adjusted by changing the current and the magnetization in the pinned layer. By optimizing the current density and the direction of the pinned magnetization, the energy pumping will be more efficient. [ABSTRACT FROM AUTHOR]

The current-excited and adjusted ferromagnetic resonance in magnetic trilayers with a tilted spin polarizer is examined. The linearization method is used for obtaining the current- and frequency-swept resonant spectra and the energy pumping will be more efficient by optimizing the current density and the direction of the pinned magnetization.