LaCrSb3: A New Itinerant Electron Ferromagnet with a Layered Structure

LaCrSb3, a new layered material, crystallizes in space group Pbcm with a = 13.266(3), b = 6.188(1), and c = 6.100(1) Å at 293 K as determined by neutron diffraction. Corrugated CrSb2 layers are stacked normal to [100] and are separated by La3+ ions and a nearly square planar Sb layer. Resistivity data indicate metallic behavior parallel to the c-axis. At low temperatures, the resistivity follows a T 2 law with an inflection point at about 125 K, above which a weaker temperature dependence is seen. Magnetization measurements also indicate a phase transition at 125 K of apparently ferromagnetic nature. A saturation moment of 0.8 μB is derived at 5 K, and a decidedly non-Curie−Weiss temperature dependence is obtained between 125 and 700 K. Neutron diffraction data verify the ferromagnetic structure at zero applied field with a moment of 0.79(3) μB/Cr and a moment direction [010]. The temperature dependence of the unit cell constants is highly anisotropic with the c-axis displaying an anomaly at T c. These properties are indicative of itinerant electron ferromagnetic behavior arising from strong electron correlation in the Cr d-bands. Band structure calculations in the extended Hückel approximation support a highly two-dimensional electronic structure comprised of contributions from Cr−Sb and Sb−Sb layers that interact very weakly along the stacking direction, a*. The Fermi level is found near a DOS maximum composed largely of Cr d-bands, but there is considerable Cr−Sb d−p mixing.