Proposal for valleytronic materials:Ferrovalley metal and valley gapless semiconductor

Valleytronic materials can provide new degrees of freedom to future electronic devices.In this work,the concepts of the ferrovalley metal(FVM)and valley gapless semiconductor(VGS)are proposed,which can be achieved in valleytronic bilayer systems by electric field engineering.In valleytronic bilayer systems,the interaction between out-of-plane ferroelectricity and A-type antiferromagnetism can induce layer-polarized anomalous valley Hall(LP-AVH)effect.The K and−K valleys of FVM are both metallic,and electron and hole carriers simultaneously exist.In the extreme case,the FVM can become VGS by analogizing spin gapless semiconductor(SGS).Moreover,it is proposed that the valley splitting enhancement and valley polarization reversal can be achieved by electric field engineering in valleytronic bilayer systems.Taking the bilayer RuBr_(2)as an example,our proposal is confirmed by the first-principle calculations.The FVM and VGS can be achieved in bilayer RuBr_(2)by applying electric field.With appropriate electric field range,increasing electric field can enhance valley splitting,and the valley polarization can be reversed by flipping electric field direction.To effectively tune valley properties by electric field in bilayer systems,the parent monolayer should possess out-of-plane magnetization,and have large valley splitting.Our results shed light on the possible role of electric field in tuning valleytronic bilayer systems,and provide a way to design the ferrovalley-related material by electric field.

Coastal blue carbon： Concept, study method, and the application to ecological restoration

Coastal blue carbon refers to the carbon taken from atmospheric CO2; fixed by advanced plants(including salt marsh,mangrove, and seagrass), phytoplankton, macroalgae, and marine calcifiers via the interaction of plants and microbes; and stored in nearshore sediments and soils; as well as the carbon transported from the coast to the ocean and ocean floor. The carbon sequestration capacity per unit area of coastal blue carbon is far greater than that of the terrestrial carbon pool. The mechanisms and controls of the carbon sink from salt marshes, mangroves, seagrasses, the aquaculture of shellfish and macroalgae, and the microbial carbon pump need to be further studied. The methods to quantify coastal blue carbon include carbon flux measurements, carbon pool measurements, manipulative experiments, and modeling. Restoring, conserving, and enhancing blue carbon will increase carbon sinks and produce carbon credits, which could be traded on the carbon market. The need to tackle climate change and implement China's commitment to cut carbon emissions requires us to improve studies on coastal blue carbon science and policy. The knowledge learned from coastal blue carbon improves the conservation and restoration of salt marshes,mangroves, and seagrasses; enhances the function of the microbial carbon pump; and promotes sustainable aquaculture, such as ocean ranching.

完善我国直接税体系的分析与思考

直接税是指税负较难转嫁的税种,由于其纳税人与负税人一致,因而强化税收调节、缩小收入及财富差距的作用明显。本文在对直接税进行明确界定的基础上,从国际比较视角对我国直接税占比变化、结构特征进行了分析。我国与世界其他主要经济体相比,直接税体系与当前经济发展阶段不相适应,结构性失衡问题凸显,个人所得税制度不完善且收入占比低,财产税结构不够合理,不利于优化收入及财富分配。健全我国直接税体系,应全方位提升直接税的职能作用,处理好直接税与间接税的关系、直接税占比提高与结构优化的关系,完善重点税制,尤其是完善个人所得税、尽快推出房地产税,构建面向自然人纳税人的征管制度体系,营造利于健全直接税体系的社会环境。