Microwave-assisted magnetization switching was investigated using Fe30Co70∕AlOx∕Ni80Fe20 magnetic tunnel junctions incorporated with a coplanar waveguide. Coercivity field of Ni80Fe20 layer was dramatically reduced in a small amplitude microwave. The authors eliminated the thermal effect in coercivity reduction by comparing two types of measurements which are with and without spin precession in the presence of microwave. It was found that the coercivity reduction depends on both frequency and power of the microwave. The numerical simulation based on Landau-Lifshitz-Gilbert equation reproduced the trend of the experimental data. The results indicate that microwave can be an efficient means to switch the magnetization of a thin film.

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The impacts of tillage system (conventional tillage and no-tillage) and residue management (0, 50, and 100%) on soil properties and soil microbial community structure were determined in the Fengqiu State Key Agro-Ecological Experimental Station, North China. The microbial community structure was investigated by phospholipid fatty acid (PLFA) profiles. The results showed that tillage had significant effects on soil properties and soil microbial communities. In no-tillage (NT), microbial biomass carbon (MBC), total N, microbial biomass carbon/soil organic carbon (MBC/SOC), total microbes, and arbuscular mycorrhiza fungi increased, while actinomycetes, G⁺/G^– bacteria ratio and monounsaturated fatty acids/saturated fatty acids (MUFA/STFA) decreased, compared with those in conventional tillage (CT). Residue had a significant positive effect on C/N ratio and MUFA/STFA. Canonical correspondence analysis indicated that tillage explained 76.1%, and residue management explained 0.6% of the variations in soil microbial communities, respectively. Soil microbial communities were significantly correlated with MBC, total N, C/N ratio and MBC/SOC. Among the six treatments, NT with 100% residue application obviously improved soil microbiological properties, and could be a proper management practice in the Huang-Huai-Hai Plain of China.  

We investigated the tunneling magnetoresistance change in magnetic tunnel junctions in the presence of external microwaves. The changing relative angle between the free layer and the pinned layer results in a rectification of the average resistance change. Due to its miniature size and its sensitivity to the microwave magnetic field, the magnetic tunnel junction could be utilized as a microwave power sensor with the ability to detect microwave frequencies. Studying microwave power and bias current dependencies reveals desired sensor features with linear responses and enhanced signal levels.