Non-collinear 2k antiferromagnetism in the Zintl semiconductor Eu$_5$In$_2$Sb$_6$

• DOI: 10.48550/arxiv.2311.00622
• Publication Date: 2023-01-01
• Authors: Vincent C. Morano; Jonathan Gaudet; Nicodemos Varnava; Tanya Berry; Thomas Halloran; Chris Lygouras; Xiaoping Wang; Christina Hoffman; Guangyong Xu; J. W. Lynn; Tyrel M. McQueen; David Vanderbilt; C. Broholm
• Keywords: Orthorhombic crystal system

Eu$_5$In$_2$Sb$_6$ is an orthorhombic non-symmorphic small band gap semiconductor with three distinct Eu$^{2+}$ sites and two low-temperature magnetic phase transitions. The material displays one of the greatest (negative) magnetoresistances known stoichiometric antiferromagnets belongs to a family Zintl materials that may host axion insulator. Using single crystal neutron diffraction, we show $T_{\mathrm{N1}}=14\mathrm{~K}$ second-order transition associated long-range antiferromagnetic order within chemical unit cell $\left( k_1 = (000) \right)$. Upon cooling below $T_{\mathrm{N1}}$, relative sublattice magnetizations this structure vary until at $T_{\mathrm{N2}}=7\mathrm{~K}$ doubles along $\hat{c}$ axis k_2 \left(00\frac{1}{2}\right) We anisotropic susceptibility our diffraction data are consistent structures described by $\Gamma_3$ irreducible representation staggered magnetization $k_1$ $k_2$ components polarized $\hat{b}$ $\hat{a}$ axis, respectively. As component develops, amplitude reduced, which indicates 2k non-collinear structure. Density functional theory used calculate energies these metal so $T_{\mathrm{N1}}$ rare example unit-cell-preserving from paramagnetic metal. DFT $T_{\mathrm{N2}}$ doubled reduces carrier density metal, resistivity data.