Bromine-doping dependence of crystal structure and superconductivity in FeSe1−xBrx

• Published in: Solid state communications Vol. 172; pp. 1 - 4
• Main Authors: Syu, K.J., Shen, Y.T., Chen, S.C., Lee, W.H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2013; Elsevier
• Subjects: A. Superconductors; B. Chemical synthesis; C. Crystal structure and symmetry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; D. Phase transitions; Effects of crystal defects, doping and substitution; Exact sciences and technology; Physics; Superconductivity; Transition temperature variations; B. Chemical synthesis; D. Phase transitions; C. Crystal structure and symmetry; A. Superconductors; Annealing; Magnetization; Tetragonal lattices; Phase transformations; Magnetic ordering; Superconducting transitions; Iron Bromides selenides; Superconductivity; Hexagonal lattices; Superconductors; Chemical composition; Crystal structure
• ISSN: 0038-1098; 1879-2766
• DOI: 10.1016/j.ssc.2013.08.001

Our experimental data indicate that the crystal structure formation in FeSe1−xBrx is dependent on the amount of Br. For the samples with x between 0.18 and 0.3, the single tetragonal β-FeSe phase with space group P4/nmm could be obtained by carrying out the low-temperature (400°C) annealing after reaction at 680°C. As to the sample with x=0.1, a heat firing at 680°C is in favor of forming single hexagonal δ-FeSe phase with space group P63/mmc. The compound FeSe0.9Br0.1 with single δ hexagonal NiAs-type phase shows neither magnetic order nor superconductivity above 1.8K according to dc magnetization measurements while the bulk character of the superconducting state with a Tc around 5K for the single β tetragonal PbO-type phase in FeSe1−xBrx is confirmed. Larger superconducting volume fraction appears in the single-phase sample with x near 0.2. •The hexagonal FeSe0.9Br0.1 and tetragonal FeSe1−xBrx (x=0.18, 0.2, 0.3) were made.•This means that the crystal structure in FeSe1−xBrx is dependent on the amount of Br.•Magnetic measurements show the superconducting Tc~5K in FeSe0.8Br0.2.