Doping-tunable Fermi surface with persistent topological Hall effect in the axion candidate EuIn2As2,Physical Review B

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Doping-tunable Fermi surface with persistent topological Hall effect in the axion candidate EuIn2As2
Physical Review B ( IF 3.2 ) Pub Date : 2024-09-09 , DOI: 10.1103/physrevb.110.115111
Jian Yan ₁ , Jianguo Si ₂ , Zhongzhu Jiang _{3,

4,

5} , Hanming Ma ₁ , Yoshiya Uwatoko ₁ , Bao-Tian Wang _{4,

6} , Xuan Luo _{3,

4} , Yuping Sun _{3,

4,

4,

7,

8,

9} , Minoru Yamashita ₁

Affiliation

The rare-earth Zintl compound

EuI n_{2} A 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

EuI n_{2} A s_{2}

is highly hole doped. Here, we synthesized a series of high-quality Ca-doped

EuI n_{2} A s_{2}

(

C a_{x} E u_{1 - x} I n_{2} A s_{2}

x = 0 – 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

C a_{x} E u_{1 - x}

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 Néel temperature and the topological Hall effect originating from the finite real-space spin chirality persist in the Ca-doped samples as observed in pristine

EuI n_{2} A s_{2}

, despite that the nonmagnetic Ca substitution decreases the effective moment and the Néel temperature. These results show that the Ca substitution tunes the Fermi energy while keeping the AFM magnetic ground state, suggesting that the axion insulating state may be realized by further Ca substitution.

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