Doping-tunable Fermi surface with persistent topological Hall effect in the axion candidate EuIn 2 As 2

作者：Jian Yan, Jianguo Si, Zhongzhu Jiang, Hanming Ma, Yoshiya Uwatoko, Bao‐Tian Wang, Xuan Luo, Yuping Sun, Minoru Yamashita · 发表于：Physical review. B./Physical review. B · 年份：2024 · DOI：10.1103/physrevb.110.115111 · 被引用次数：4 · 研究领域：Topological Materials and Phenomena、Cold Atom Physics and Bose-Einstein Condensates、Physics of Superconductivity and Magnetism

The rare-earth Zintl compound $\mathrm{EuI}{\mathrm{n}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ has been theoretically recognized as a candidate for realizing an intrinsic antiferromagnetic (AFM) bulk axion insulator and a higher-order topological state, which provides a fertile platform to explore novel topological transport phenomena. However, the axion state has yet to be realized because $\mathrm{EuI}{\mathrm{n}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ is highly hole doped. Here, we synthesized a series of high-quality Ca-doped $\mathrm{EuI}{\mathrm{n}}_{2}\mathrm{A}{\mathrm{s}}_{2}$ ($\mathrm{C}{\mathrm{a}}_{x}\mathrm{E}{\mathrm{u}}_{1\ensuremath{-}x}\mathrm{I}{\mathrm{n}}_{2}\mathrm{A}{\mathrm{s}}_{2}$, $x=0\text{--}0.25$) single crystals to tune the Fermi energy above the hole pocket. Our Hall measurements reveal that the Ca substitution decreases the hole carrier density. This decrease is brought by the lattice contraction and the effective electron doping by a slight increase of the valence charge of $\mathrm{C}{\mathrm{a}}_{x}\mathrm{E}{\mathrm{u}}_{1\ensuremath{-}x}$ as $x$ increases, confirmed by our first-principles calculations. We further find that both the temperature dependence of the magnetic susceptibility with a local maximum at the N\'eel temperature and the topological Hall effect originating from the finite real-space spin chirality persist in the Ca-doped samples as observed in pristine $\mathrm{EuI}{\mathrm{n}}_{2}\mathrm{A}{\mathrm{s}}_{2}$, despite that the nonmagnet...