A-type antiferromagnetic order in semiconducting EuMg${}_2$Sb${}_2$ single crystals

Abstract

Eu-based Zintl-phase materials EuA${}_2$Pn${}_2$ (A = Mg, In, Cd, Zn; Pn = Bi, Sb, As, P) have generated significant recent interest owing to the complex interplay of magnetism and band topology. Here, we investigated the electronic, magnetic, and electronic properties of the layered Zintl-phase single crystals of EuMg${}_2$Sb${}_2$ with the trigonal CaAl${}_2$Si${}_2$ crystal structure (space group $P\bar{3}m1$). Electrical resistivity measurements complemented with angle-resolved photoemission spectroscopy (ARPES) studies find an activated behavior with the intrinsic conductivity at high temperatures indicating a semiconducting electronic ground state with a narrow energy gap of 370 meV. Magnetic susceptibility and zero-field heat-capacity measurements indicate that the compound undergoes antiferromagnetic (AFM) ordering at the Neel temperature $T_{\mathrm{N}}$ = 8.0(2) K. Zero-field neutron-diffraction measurements reveal that the AFM ordering is A-type where the Eu ordered moments (Eu${}^{2+}$, S= 7/2) arranged in ab-plane layers are aligned ferromagnetically in the ab plane with the Eu moments in adjacent layers aligned antiferromagnetically. We also find that Eu-moment reorientation in the trigonal AFM domains within the ab planes occurs below $T_{\mathrm{N}}$ at low fields < 0.05 T due to very small in-plane anisotropy. Although isostructural semimetallic EuMg${}_2$Bi${}_2$ is reported to host Dirac surface states, the observation of narrow-gap semiconducting behavior in EuMg${}_2$Sb${}_2$ implies a strong role of spin-orbit coupling in tuning the electronic states of these materials.

15 pages, 15 captioned figures, 33 references

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Cited by in corpus (10)

• Anisotropic magnetism and electronic structure of trigonal EuAl${}_2$Ge${}_2$ single crystals
• Superexchange Interaction in Insulating EuZn${}_2$P${}_2$
• Ambient and high pressure studies of structural, electronic and magnetic properties of EuZn${}_2$P${}_2$ single crystal
• A Map of the Zintl AM2Pn2 Compounds: Influence of Chemistry on Stability and Electronic Structure
• Magnetic-field-induced ab-plane rotation of the Eu magnetic moments in trigonal EuMg2Bi2 and EuMg2Sb2 single crystals below their Neel temperatures
• Field-tunable Weyl points and large anomalous Hall effects in degenerate magnetic semiconductor EuMg${}_2$Bi${}_2$
• Low-field magnetic anomalies in single crystals of the A-type square-lattice antiferromagnet EuGa${}_4$
• Recent advances in understanding and manipulating magnetic and electronic properties of Eu$M_2{X}_2$ ($M$ = Zn, Cd; $X$ = P, As)
• Origin of the large topological Hall effect in the EuCd${}_2$Sb${}_2$ antiferromagnet
• Anomalous temperature-dependent magnetization in the nearly collinear antiferromagnet Y${}_2$Co${}_3$