Growth of millimeter-sized high-quality CuFeSe2 single crystals by the molten salt method and study of their semiconducting behavior

An eutectic AlCl3/KCl molten salt method in a horizontal configuration was employed to grow millimeter-sized and composition homogeneous CuFeSe2 single crystals due to the continuous growth process in a temperature gradient induced solution convection. The typical as-grown CuFeSe2 single crystals in cubic forms are nearly 1.6 x 1.2 x 1.0 mm3 in size. The chemical composition and homogeneity of the crystals was examined by both inductively coupled plasma atomic emission spectroscopy and energy dispersive spectrometer with Cu:Fe:Se = 0.96:1.00:1.99 consistent with the stoichiometric composition of CuFeSe2. The magnetic measurements suggest a ferrimagnetic or weak ferromagnetic transition below TC = 146 K and the resistivity reveals a semiconducting behavior and an abrupt increase below TC.