Magnetism and superconductivity in Sb-doped binary and ternary iron chalcogenide single crystals

• Sb doped Fe1+yTe and Fe1+yTe0.5Se0.5 single crystals are grown by modified horizontal Bridgman.
• Structural, magnetic and transport properties of single crystals are studied.
• Doping modifies the magnetic properties in Fe1+yTe and superconductivity in Fe1+yTe0.5Se0.5.
• Antiferromagnetic transition, TN in Fe1+yTe at 62.2 K falls to 56.5 K on 2% Sb doping.
• Sb doping in Fe1+yTe0.5Se0.5 results in superconductivity with a transition temperature TC=8 K.

We report the single crystal growth of antimony doped Fe1+yTeFe1+yTe and Fe1+yTe0.5Se0.5Fe1+yTe0.5Se0.5 (Fe1+ySbxTe1−xFe1+ySbxTe1−x (x  =0, 2%, 5%) and Fe1+yTe0.49Se0.49Sb0.02Fe1+yTe0.49Se0.49Sb0.02) by a modified horizontal Bridgman method. Growth parameters are optimized to obtain high quality single crystals. The antiferromagnetic (AFM) transition at TN=62.2 K which is a first order transition, shifts to lower temperature on doping in Fe1+yTeFe1+yTe. Alternately when the chalcogen site of the ternary compound Fe1+yTe0.5Se0.5Fe1+yTe0.5Se0.5 is doped with Sb, superconductivity is preserved albeit the superconducting transition temperature (TC) falls slightly and a concomitant reduction occurs in superconducting volume fraction.