Sign-reversed anomalous Nernst effect in the ferromagnetic Weyl-semimetal Fe3−δGeTe2: the role of Fe vacancies
Sign-reversed anomalous Nernst effect in the ferromagnetic Weyl-semimetal Fe3−δGeTe2: the role of Fe vacancies
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铁磁外尔半金属 Fe3–δGeTe2 中符号反转的反常能斯特效应：Fe 空位的作用
DOI：
10.1007/s11433-022-1938-0
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Yuke Li
中科院分区：
文献类型：
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作者：
Haiyang Yang;Qi Wang;Junwu Huang;Zhouliang Wang;Keqi Xia;Chao Cao;Mingliang Tian;Zhuan Xu;Jianhui Dai;Yuke Li
反常能斯特效应作为反常霍尔效应的热伙伴，对费米能级附近的Berry曲率反常特别敏感，已被用于探索量子材料的拓扑性质。在这项工作中，我们报告了在具有可调Fe空位的铁磁Weyl半金属Fe3−δGeTe2中观察到的这两种效应。随着Fe空位的减少，反常的霍尔电导率作为纵向电导率的函数从跳跃区域演化到本征Berry曲率贡献占主导地位的区域。在居里温度以下观察到异常能斯特信号和异常非对角热电系数的伴随演变，显示出由Fe空位引起的独特的符号变化。结合这些结果与第一性原理计算，我们认为，铁空位浓度起着独特的作用，同时调整的化学势和铁磁性，这反过来又控制了这个家庭的铁磁性拓扑半金属的Berry曲率贡献。
Anomalous Nernst effect, as a thermal partner of anomalous Hall effect, is particularly sensitive to the Berry curvature anomaly near the Fermi level, and has been used to probe the topological nature of quantum materials. In this work, we report the observation of both effects in the ferromagnetic Weyl-semimetal Fe3−δGeTe2 with tunable Fe vacancies. With decreasing Fe vacancies, the anomalous Hall conductivity evolves as a function of the longitudinal conductivity from the hopping region to the region where the intrinsic Berry curvature contribution dominates. Concomitant evolutions in the anomalous Nernst signal and the anomalous off-diagonal thermoelectric coefficient are observed below the Curie temperature, displaying a unique sign change caused by the Fe vacancies. Combining these results with first-principles calculations, we argue that the Fe-vacancy concentration plays a unique role in simultaneously tuning the chemical potential and ferromagnetism, which in turn controls the Berry curvature contribution in this family of ferromagnetic topological semimetals.