反常能斯特效应是指在外磁场为零时，施加纵向的温度梯度也能够产生一个横向的电压。它已经在传统铁磁体中被观察和研究，并被认为反常能斯特信号正比于自发磁化强度。然而，具有手性磁效应的拓扑外尔半金属体系可能不遵循这个关系，其反常能斯特效应的机理以及与Berry曲线的联系都亟待探索研究。本项目以磁性Co3Sn2S2和非磁性NbP(As)两类外尔半金属为研究对象，通过系统的能斯特效应测量：(1)研究样品强磁场下的Nernst效应量子震荡行为，获取费米面拓扑结构信息；(2) 研究两类外尔半金属的能斯特效应，揭示巨大反常能斯特效应的来源及其与磁化强度的函数关系，探明体系内秉的拓扑Weyl态以及与Berry曲线的内在联系；(3) 定量分析铁磁态和非平庸Berry曲线对反常能斯特信号的贡献，揭示拓扑Weyl体系与传统铁磁体产生反常能斯特效应的区别和联系。

Anomalous Nernst effect (ANE) is that a transverse voltage can be generated by a longitudinal temperature gradient even in absent of magnetic field. This effect has been observed and investigated in conventional ferromagnets and its signal was believed to scale with spontaneous magnetization. However, topological Weyl semimetals associated with the chiral magnetic effect does not follow the scale relation. Thus the study of the mechanism of ANE as well as the relationship between ANE and Berry curvature is highly desirable. In this project, we will focus on the magnetic Co3Sn2S2 and non-magnetic NbP(As) topological Weyl semimetals, and through the measurement of Nernst effect, we will investigate: (1) By measuring the quantum oscillations of Nernst effect under high magnetic fields, giving the information of the Fermi Surface topological structures. (2) Measuring the Nernst effect in both systems, discovering the origin of giant anomalous Nernst effect and the relationship between ANE and magnetization, and then exploring the intrinsic topological Weyl state as well as the relationship of Nernst effect and non-trivial Berry curvature; (3) By investigating the anomalous Nernst effect, quantificationally describing the Nernst signal originated from the contributions of ferromagnetic order and Berry curvature, respectively, and revealing the difference and the relationship between them.