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 (chi), magnetization (M), resistivity (rho), specific heat (C), and thermal expansion (alpha). We also report high-resolution powder x-ray diffraction data that support a structural phase transition with accompanying signatures seen in C(T), rho (T), and alpha(T). We find Eu7Ga6Sb8 exhibits antiferromagnetic ordering at T-N1 = 9.0 K from anomalies seen in chi(T), C(T), and alpha(T), as well as a potential reorientation of Eu2+ spins at T-N2 = 7.5 K and T-N3 = 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.