Anisotropic magneto-transport properties of layered perovskite Sr₃Fe_2-xCo_xC_7-δ crystals

We have grown a series of single crystals of layered perovskite oxide Sr₃Fe_2-xCo_xO_7-δ (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) and systematically investigated anisotropic properties of magnetism and transport as a function of x. The magnetization and resistivity of Sr₃Fe_2-xCo_xO_7-δ crystals exhibit a large anisotropy due to the highly anisotropic crystal structure: the magnetic easy axis is found to be the c axis (perpendicular to the layered structure), and the resistivity within the ab plane (within the layer) is much lower than that along the c axis. With increasing x up to 0.5, the emergence of ferromagnetic behavior with a nearly metallic conduction was observed.