Structural and Transport Studies of Under Doped FeTe1-xSex(x=0.0, 0.01, 0.03, 0.05) Single Crystals

Abstract: We report synthesis of under doped non-superconducting parent compound of iron chalcogenide, i.e FeTe1-xSex (x=0.0, 0.01, 0.03, 0.05) single crystals by flux free method. These FeTe1-xSex (x=0.0, 0.01, 0.03, 0.05) single crystals are crystallized in the tetragonal structure with space group P4/nmm at room temperature. Detailed scanning electron microscopy (SEM) results showed that the crystals are formed in slab-like morphology structure. Powder X-Ray diffraction (XRD) results show that (0 0 l) peaks are shifted towards higher angel with increasing Se concentration. Coupled magnetic and structural phase transition temperature, being seen as a step in resistivity, decreases from around 67K for x = 0.0 to 55K for x = 0.05 crystal. Further, the step in resistivity is seen to be hysteric ({\Delta}T) in nature, i.e., different step temperatures in cooling and warming cycles. Interestingly, the hysteric ({\Delta}T) becomes narrower from around 5.8K for x =0.0 to 0.95K for x =0.05 crystal.