Structural transition and anisotropic magnetism in disordered Zintl phase Eu7Ga6Sb8

Single crystals of the Zintl compound Eu₇Ga₆Sb₈ were synthesized using a Ga-Sb flux. We report the temperature (T ) and magnetic field (H ) dependence of the magnetic susceptibility (χ ), magnetization (M ), resistivity (ρ ), specific heat (C ), and thermal expansion (α ). We also report high-resolution powder x-ray diffraction data that support a structural phase transition with accompanying signatures seen in C (T ) , ρ (T ) , and α (T ) . We find Eu₇Ga₆Sb₈ exhibits antiferromagnetic ordering at T_{N 1}=9.0 K from anomalies seen in χ (T ) , C (T ) , and α (T ) , as well as a potential reorientation of Eu2⁺ spins at T_{N 2}=7.5 K and T_{N 3}=7.2 K. Density functional theory calculations predict Eu₇Ga₆Sb₈ to be semiconducting; however, electrical resistivity measurements show bad-metal behavior that indicates the presence of disorder.