Narrow-gap semiconducting behavior in antiferromagnetic Eu11InSb9

Abstract

Here we investigate the thermodynamic and electronic properties of ${\mathrm{Eu}}_{11}\mathrm{In}{\mathrm{Sb}}_{9}$ single crystals. Electrical transport data show that ${\mathrm{Eu}}_{11}\mathrm{In}{\mathrm{Sb}}_{9}$ has a semiconducting ground state with a relatively narrow band gap of 320 meV. Magnetic susceptibility data reveal antiferromagnetic order at low temperatures, whereas ferromagnetic interactions dominate at high temperature. Specific heat, magnetic susceptibility, and electrical resistivity measurements reveal three phase transitions at ${T}_{N1}=9.3$ K, ${T}_{N2}=8.3$ K, and ${T}_{N3}=4.3$ K. Unlike ${\mathrm{Eu}}_{5}{\mathrm{In}}_{2}{\mathrm{Sb}}_{6}$, a related europium-containing Zintl compound, no colossal magnetoresistance (CMR) is observed in ${\mathrm{Eu}}_{11}\mathrm{In}{\mathrm{Sb}}_{9}$. We attribute the absence of CMR to the smaller carrier density and the larger distance between Eu ions and In-Sb polyhedra in ${\mathrm{Eu}}_{11}\mathrm{In}{\mathrm{Sb}}_{9}$. Our results indicate that ${\mathrm{Eu}}_{11}\mathrm{In}{\mathrm{Sb}}_{9}$ has potential applications as a thermoelectric material through doping or as a long-wavelength detector due to its narrow gap.