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In the past two decades, high entropy alloy (HEA) coatings have attracted great attention due to their superior mechanical properties, outstanding corrosion and oxidation resistance, and exceptionally high thermal stability. In comparison to HEA thin films, high entropy nitrides (HENs) exhibit higher mechanical strength and chemical inertness. In this work, AlCrFeCoNiCu0.5 HEA and HEN thin films were fabricated using a filtered cathodic arc. By regulating the deposition pressure from 0.0005 Pa (HEA thin film) to 0.05 Pa, the nitrogen concentration in each thin film was precisely controlled to tune the mechanical properties. Scanning transmission electron microscopy-energy dispersive spectroscopy revealed that the nitrogen concentration of the films was up to 21.2 at. % at the pressure of 0.05 Pa. The reduced effect of preferential sputtering increased aluminum concentration from 8.3 ± 1.5 to 12.9 ± 2.2 at. % as pressure increased up to 0.05 Pa. X-ray photoelectron spectroscopy further confirmed the formation of AlN and CrN at pressures of 0.01–0.05 Pa. The highest hardness and elastic modulus of the HEN film were 12.4 ± 0.6 and 347.3 ± 17.7 GPa, respectively, which were 84.8% and 131.4% higher than those of the HEA thin film. [ABSTRACT FROM AUTHOR]

The nonlocal spin valve configuration consists of two ferromagnetic and nonmagnetic channels, which is an effective configuration for determining spin injection and accumulation. Here, we report that a reversed nonlocal spin signal was detected by changing the voltage probe configurations in graphene (Py/MgO/graphene/MgO/Py) lateral spin valves. The abnormal reversed spin-dependent nonlocal voltage is attributed to the nonuniform pinhole at the interface of the low-resistance tunnel barrier, which makes the charge current flow through the detection electrode and return to the graphene channel. We demonstrate that the channel-width induced spin-polarized current inhomogeneity significantly contributes to nonlocal resistance. A detailed description and simulated results of the tunnel junctions provide evidence for the reversal of the nonlocal voltage sign induced by the low-resistance tunnel barriers. Our work sheds light on the understanding of the spatial distribution of the spin current and the effect of the tunnel barrier, which are essential for the development of spintronic devices. [ABSTRACT FROM AUTHOR]