高磁各向异性拓扑节点线MnAlGe中反常能斯特效应的室温极性控制
Room-Temperature Polarity Control of the Anomalous Nernst Effect in a High-Magnetic-Anisotropy Topological Nodal-Line MnAlGe
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中文总结 AI 辅助
研究人员通过Al/Ge组分调控，在保留高磁各向异性的拓扑节点线MnAlGe外延薄膜中实现了反常能斯特效应的室温极性控制，结合正负极性材料制备的器件可提升热电输出，为室温横向热电器件提供了新路径。
中文摘要 AI 辅助
控制反常能斯特热电势的极性是提升热电应用性能的可行策略，但在具有高磁各向异性（Ku）的拓扑铁磁体中实现室温（RT）下的此类控制仍具挑战性。本文报道，通过Al/Ge组分调控，在准二维节点线MnAlGe外延薄膜中实现了反常能斯特效应（ANE）的室温极性控制，同时保留了稳定的高Ku。这种极性反转源于子晶格选择性载流子掺杂调控的固有贝里曲率贡献，自旋分辨电子能带结构分析和硬X射线光电子能谱均证实了这一点。为验证实际可行性，我们还制备了蜿蜒结构器件，将正、负极性增强型MnAlGe结合，提升了热电输出。研究表明，在保留高Ku的同时，调控费米能级相对于节点线电子结构的位置，可在单一材料中实现可控的ANE极性反转，为室温横向热电器件提供了途径。
英文摘要
Controlling the polarity of anomalous Nernst thermopower is a promising strategy for enhancing the performances of thermoelectric applications. However, realizing such control at room temperature (RT) in topological ferromagnets with high magnetic anisotropy (Ku) remains challenging. Here, we report RT polarity control of the anomalous Nernst effect (ANE) in quasi-two-dimensional nodal-line MnAlGe epitaxial thin films through Al/Ge compositional tuning while preserving robust high Ku. This polarity reversal originates from intrinsic Berry curvature contributions modulated by sublattice-selective carrier doping, as supported by spin-resolved electronic band structure analysis and hard X-ray photoemission spectroscopy. To demonstrate the practical feasibility, we also fabricated a meander-structured device combining MnAlGe with positive and negative polarity enhanced the thermoelectric output. Our results demonstrate that tuning the Fermi level relative to the nodal-line electronic structure while preserving high Ku enables controllable ANE polarity reversal within a single material, providing a route toward RT transverse thermoelectric devices.
