Structural and resistivity properties of Fe${}_{1-x}$Co${}_x$Se single crystals grown by the molten salt method

Abstract

A series of tetragonal Fe${}_{1-x}$Co${}_x$Se single crystals with a complete Co doping range (0$\le$x$\le$0.52) up to its solid solubility limit in FeSe have been grown by an eutectic AlCl${}_3$/KCl molten salt method. The typical lateral size of as-grown Fe${}_{1-x}$Co${}_x$Se single crystals is 1$-$5 mm. The chemical composition and homogeneity of the crystals was examined by both inductively coupled plasma atomic emission spectroscopy and energy dispersive spectrometer. X-ray diffraction analysis demonstrates that the crystal lattice parameters $a$ and $c$ are both linearly decreased with increasing Co doping level x. In the whole doping range, all the samples show metallic behaviour in contrast to a metal insulator transition of Cu-doped FeSe according to the resistivity measurements