Source abstract
Abstract
${\mathrm{Eu}}5{\mathrm{In}}2{\mathrm{Sb}}6$ is an orthorhombic nonsymmorphic small band gap semiconductor with three distinct ${\mathrm{Eu}}2+$ sites and two low-temperature magnetic phase transitions. The material displays one of the greatest (negative) magnetoresistances of known stoichiometric antiferromagnets and belongs to a family of Zintl materials that may host an axion insulator. Using single crystal neutron diffraction, we show that the ${T}_{\mathrm{N}1}=14\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ second-order phase transition is associated with long-range antiferromagnetic order within the chemical unit cell $({\mathbf{k}}1=(000))$. Upon cooling below ${T}_{\mathrm{N}1}$, the relative sublattice magnetizations of this structure vary until a second-order phase transition at ${T}_{\mathrm{N}2}=7\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ that doubles the unit cell along the $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathbf{c}}$ axis $({\mathbf{k}}2=(00\frac{1}{2}))$. We show the anisotropic susceptibility and our magnetic neutron diffraction data are consistent with magnetic structures described by the ${\mathrm{\ensuremath{\Gamma}}}3$ irreducible representation with the staggered magnetization of the ${\mathbf{k}}1$ and ${\mathbf{k}}2$ components polarized along the $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathbf{b}}$ and $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathbf{a}}$ axis, respectively. As the ${\mathbf{k}}2$ component develops, the amplitude of the ${\mathbf{k}}1$ component is reduced, which indicates a $2\mathbf{k}$ noncollinear magnetic structure. Density functional theory is used to calculate the energies of these magnetic structures and to show the ${\mathbf{k}}1$ phase is a metal so ${T}_{\mathrm{N}1}$ is a rare example of a unit-cell-preserving second-order phase transition from a paramagnetic semiconductor to an antiferromagnetic metal. DFT indicates the transition at ${T}_{\mathrm{N}2}$ to a doubled unit cell reduces the carrier density of the metal.
Source: openalex_inverted_index · Quality: baseline
Affiliations
Institute for Quantum Matter and William H. Miller III Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102, USA
Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742-2115, USA
Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854, USA
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
Funding
Energy Frontier Research Centers · U.S. Department of Energy · Office of Science · Basic Energy Sciences · National Institute of Standards and Technology · Oak Ridge National Laboratory · National Science Foundation · Gordon and Betty Moore Foundation