P. Gong et al. land-cover classification system as well as the International Geosphere-Biosphere Programme (IGBP) system. Using the four classification algorithms, we obtained the initial set of global land-cover maps. The SVM produced the highest overall classification accuracy (OCA) of 64.9% assessed with our test samples, with RF (59.8%), J4.8 (57.9%), and MLC (53.9%) ranked from the second to the fourth. We also estimated the OCAs using a subset of our test samples (8629) each of which represented a homogeneous area greater than 500 m × 500 m. Using this subset, we found the OCA for the SVM to be 71.5%. As a consistent source for estimating the coverage of global land-cover types in the world, estimation from the test samples shows that only 6.90% of the world is planted for agricultural production. The total area of cropland is 11.51% if unplanted croplands are included. The forests, grasslands, and shrublands cover 28.35%, 13.37%, and 11.49% of the world, respectively. The impervious surface covers only 0.66% of the world. Inland waterbodies, barren lands, and snow and ice cover 3.56%, 16.51%, and 12.81% of the world, respectively.

The spin Hall angle (SHA) is a measure of the efficiency with which a transverse spin current is generated from a charge current by the spin-orbit coupling and disorder in the spin Hall effect (SHE). In a study of the SHE for a Pt|Py (Py=Ni_{80}Fe_{20}) bilayer using a first-principles scattering approach, we find a SHA that increases monotonically with temperature and is proportional to the resistivity for bulk Pt. By decomposing the room temperature SHE and inverse SHE currents into bulk and interface terms, we discover a giant interface SHA that dominates the total inverse SHE current with potentially major consequences for applications.

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Soil respiration (Rs) represents the largest flux of CO2 from terrestrial ecosystems to the atmosphere, but its spatial and temporal changes as well as the driving forces are not well understood. We derived a product of annual global Rs from 2000 to 2014 at 1 km by 1 km spatial resolution using remote sensing data and biome-specific statistical models. Different from the existing view that climate change dominated changes in Rs, we showed that land-cover change played a more important role in regulating Rs changes in temperate and boreal regions during 2000–2014. Significant changes in Rs occurred more frequently in areas with significant changes in short vegetation cover (i.e., all vegetation shorter than 5 m in height) than in areas with significant climate change. These results contribute to our understanding of global Rs patterns and highlight the importance of land-cover change in driving global and regional Rs changes.

In the present work, reduced graphene oxide (rGO)/poly(N-isopropylacrylamide) (PNIPAA) composite films were electrodeposited onto the surface of Au electrodes in a fast and one-step manner from an aqueous mixture of a graphene oxide (GO) dispersion and N-isopropylacrylamide (NIPAA) monomer solutions. Reflection-absorption infrared (IR) and Raman spectroscopies were employed to characterize the successful construction of the rGO/PNIPAA composite films. The rGO/PNIPAA composite films exhibited reversible potential-, pH-, temperature-, and sulfate-sensitive cyclic voltammetric (CV) on-off behavior to the electroactive probe ferrocenedicarboxylic acid (Fc(COOH)2). For instance, after the composite films were treated at -0.7 V for 7 min, the CV responses of Fc(COOH)2 at the rGO/PNIPAA electrodes were quite large at pH 8.0, exhibiting the on state. However, after the films were treated at 0 V for 30 min, the CV peak currents became much smaller, demonstrating the off state. The mechanism of the multiple-stimuli switchable behaviors for the system was investigated not only by electrochemical methods but also by scanning electron microscopy and X-ray photoelectron spectroscopy. The potential-responsive behavior for this system was mainly attributed to the transformation between rGO and GO in the films at different potentials. The film system was further used to realize multiple-stimuli responsive bioelectrocatalysis of glucose catalyzed by the enzyme of glucose oxidase and mediated by the electroactive probe of Fc(COOH)2 in solution. On the basis of this, a four-input enabled OR (EnOR) logic gate network was established.

Electric field (E-field) modulation of perpendicular magnetic anisotropy (PMA) switching, in an energy-efficient manner, is of great potential to realize magnetoelectric (ME) memories and other ME devices. Voltage control of the spin-reorientation transition (SRT) that allows the magnetic moment rotating between the out-of-plane and the in-plane direction is thereby crucial. In this work, a remarkable magnetic anisotropy field change up to 1572 Oe is achieved under a small operation voltage of 4 V through ionic liquid (IL) gating control of SRT in Au/[DEME] [TFSI] /Pt/(Co/Pt) /Ta capacitor heterostructures at room temperature, corresponding to a large ME coefficient of 378 Oe V . As revealed by both ferromagnetic resonance measurements and magnetic domain evolution observation, the magnetization can be switched stably and reversibly between the out-of-plane and in-plane directions via IL gating. The key mechanism, revealed by the first-principles calculation, is that the IL gating process influences the interfacial spin-orbital coupling as well as net Rashba magnetic field between the Co and Pt layers, resulting in the modulation of the SRT and in-plane/out-of-plane magnetization switching. This work demonstrates a unique IL-gated PMA with large ME tunability and paves a way toward IL gating spintronic/electronic devices such as voltage tunable PMA memories.

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Effective spin mixing conductance (ESMC) across the nonmagnetic metal (NM)/ferromagnet interface, spin Hall conductivity (SHC) and spin diffusion length (SDL) in the NM layer govern the functionality and performance of pure spin current devices with spin pumping technique. We show that all three parameters can be tuned significantly by the spin orbit coupling (SOC) strength of the NM layer in systems consisting of ferromagnetic insulating Y 3 Fe 5 O 12 layer and metallic Pd 1−x Pt x layer. Surprisingly, the ESMC is observed to increase significantly with x changing from 0 to 1.0. The SHC in PdPt alloys, dominated by the intrinsic term, is enhanced notably with increasing x. Meanwhile, the SDL is found to decrease when Pd atoms are replaced by heavier Pt atoms, validating the SOC induced spin flip scattering model in polyvalent PdPt alloys. The capabilities of both spin current generation and spin charge conversion are largely heightened via the SOC. These findings highlight the multifold tuning effects of the SOC in developing the new generation of spintronic devices.