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Two-dimensional (2D) transition metal dichalcogenides with 2H-phases, as a unique platform of valleytronics, display valley polarization and the well-known anomalous valley Hall effect when stacking with 2D magnetic substrates. In this study, we employ first-principles calculations to investigate the magnetic states, band structures, and magnetic proximity-dependent valley properties of 2D van der Waals heterostructures Cr2Ge2Te6/2H-MX2 (M = Mo, W, and X = S, Se, Te). Our findings reveal that the heterostructures possess stacking-dependent spontaneous valley polarization as well as pristine perpendicular magnetic anisotropy. Additionally, the Berry curvature and circular polarization demonstrate the presence of spin–momentum coupling characteristics, while the calculated non-zero Hall voltage indicates that the anomalous valley Hall effect can be achieved in valley-polarized systems. Furthermore, due to the strain effect and the electronic polarization at the interface, Cr2Ge2Te6/2H-MX2 heterostructures undergo the transition from semiconductors to semimetals upon substitution of early chalcogen elements. These calculations provide valuable insights for practical applications of valleytronics in 2D van der Waals heterostructure systems. [ABSTRACT FROM AUTHOR]

Advancements and utilization of magnetic refrigeration technology hinge on the ongoing enhancement and optimization of magnetic refrigeration material properties. Nevertheless, the intricacy of the magnetocaloric effect (MCE) mechanism has emerged as a bottleneck, constraining the progress and refinement of magnetic refrigeration materials. In this study, a classic magnetic system is chosen to investigate the mechanism of MCE across four different scales–macroscopic magnetism, micrometer‐scale magnetic domains, atomic magnetic moments, and electronic structure. It simultaneously exhibits two inverse MCEs and one direct MCE, with a working temperature span as wide as 125 K (most are <50 K) for the direct MCE. The measurements of the vibrating sample magnetometer, in situ Lorentz electron microscopy and variable‐temperature neutron powder diffraction directly reveal that the complex magnetic entropy changes arise from the magnetic domain wall pinning, the instability of Ho magnetic moments, and the spin rotation. First‐principles calculations elucidate the crucial role of strong hybridization between localized Ho and itinerant Co electrons in the spin reorientation of HoCo4Al. This study contributes significantly to comprehending the induction mechanism of the MCE and holds vital reference value for exploring new magnetic refrigeration materials and enhancing MCE performance. [ABSTRACT FROM AUTHOR]

Against the backdrop of rapid global economic development, the Beijing-Tianjin-Hebei (BTH) region, a pivotal economic hub and environmentally sensitive area in China, faces significant challenges in sustaining its landscape ecosystem. Given the region's strategic importance and vulnerability to environmental pressures, this study investigated the intricate relationships between landscape ecological risk, urban expansion, and economic growth (EG) in the BTH region. Utilizing the landscape as the focal point, we constructed a decoupling model at the grid scale to explore the decoupling relationship between the landscape ecological risk index (ERI), construction area growth (CAG), and EG. The results showed that (1) distinct stages and regional disparities were observed in the trends of ERI, CAG, and EG within the BTH region. The hot and cold spot patterns for these factors did not align consistently. (2) From 1995 to 2019, the coupling relationship between ERI, CAG, and EG in the BTH region underwent a fluctuating transition, initially moving from an undesirable state to an ideal state, and subsequently reverting to an undesirable state. Although the overall trends in these relationships showed some convergence, there were notable spatial distribution differences. (3) The spatial heterogeneity of the two decoupling relationships in the BTH region was relatively poor. Further analysis revealed that the evolution of these decoupling relationships was closely intertwined with regional policy shifts and adjustments. [ABSTRACT FROM AUTHOR]

With the development of urban agglomerations in China, the study of the interactions between cities has become a popular and difficult issue. Exploring the interactions between cities can help decision-makers optimize regional resource allocation and improve regional spatial patterns. Combining the urban flow model and the patch-generating land use simulation (PLUS) model, this study simulates and analyzes the process of urban expansion in the Beijing–Tianjin–Hebei (BTH) region, and investigates the impact of urban hierarchical structure differences on urban expansion. In this study, the role and influence of inter-city economy flow, transportation flow, population flow, and information flow on the development of urban agglomerations are comprehensively considered, and a multilevel urban interaction model is constructed based on a hierarchical generalized linear model (HGLM). Based on the national BTH cooperation and development strategy, a multi-scenario simulation study of urban expansion is carried out using the HGLM-PLUS model. The results indicate the following: (1) compared to the traditional PLUS model, the coupled HGLM-PLUS model, which considers multilevel urban flows, improved the overall accuracy by 0.047, the Kappa coefficient by 0.207, and the figure of merit (FoM) index by 0.051; (2) under different simulation scenarios, the development trend under the cooperation and development policy in the BTH region is more stable, demonstrating a relatively smooth urbanization expansion trend; and (3) under the BTH cooperation and development background, the total area of construction land in the BTH region is expected to be maintained at around 1,164,500 km2 by 2040. The spatial expansion pattern will present a networked expansion with the core driving development, axes and belts connecting, and clusters breaking through. [ABSTRACT FROM AUTHOR]

Exploring and discovering various types of skyrmions has enriched the fundamental study and the active skyrmionics aiming at using skyrmions in spintronics due to the advantages of global stability as high-density magnetic information bit. The unique capability to introduce abundant spin structures, physical phenomena, and dynamics due to the interactions of 4f and 3d electrons push the rare-earth–transition metal (RE–TM) magnets into the research frontier again. Herein, the exotic magnetic domain configurations are discovered in traditional ThMn12-type RE–TM magnets. It is clearly demonstrated that the magnetic anisotropy alteration and magnetic coupling between the respective RE and TM sublattices are responsible for the abundant magnetic domain evolution. In particular, the field-free biskyrmions at room temperature and tunable spin texture transformation are successfully obtained via manipulating the in-plane magnetic anisotropy, which has broadened the physical mechanism and application exploration of manipulating ferrimagnetic order to generate topological spin structures in strategic rare-earth magnets. [ABSTRACT FROM AUTHOR]

Landscape-index calculation tools play a pivotal role in ecosystem studies and urban-planning research, enabling objective assessments of landscape patterns' similarities and differences. However, the existing tools encounter limitations, such as the inability to visualize landscape indices spatially and the challenge of computing indices for both vector and raster data simultaneously. Based on the QGIS development platform, this study presents an innovative framework for landscape-index calculation that addresses these limitations. The framework seamlessly integrates both vector and raster data, comprising three main modules: data input, landscape-index calculation, and visualization. In the data-input module, the tool accommodates various data formats, including vector, raster, and tabular data. The landscape indices' calculation module allows users to select indices at patch, class, and landscape scales. Notably, the framework provides a comprehensive set of 165 indices for vector data and 20 for raster data, empowering users to selectively calculate landscape indices for vector or raster data to their specific needs and leverage the strengths of each data type. Moreover, the landscape-index visualization module enhances spatial visualization capabilities, meeting user demands for an insightful analysis. By addressing these challenges and offering enhanced functionalities, this framework aims to advance landscape indices' development and foster more comprehensive landscape analyses. And it presents a novel approach for landscape-index development. [ABSTRACT FROM AUTHOR]