Growth and Investigation of Crystals of the New Superconductor α-FeSe from KCl Solutions

Abstract

Crystals of FeSe 0.88 and FeSeMn 0.1 have been grown from KCl solutions. Crystals measuring 2−3 mm across and 0.1−0.3 mm thick grow with a hexagonal plate like habit. Powder X-ray diffraction (XRD) measurements show strong peaks corresponding to the tetragonal α-FeSe phase and weak hexagonal β-FeSe peaks in both cases. The plate side of the crystal is identified to be the (101) face of the tetragonal α-FeSe. Energy dispersive X-ray spectroscopic (EDS) measurements show that Mn substitutes for Fe. Both types of crystals show a superconducting transition at 8 K in the DC magnetization measurements and a broad resistive transition with zero resistance at 7.5 K with an onset at 11 K. Specific heat measurements also confirm bulk superconductivity in the crystals. Crystals could also be grown using KBr as a solvent.