Synthesis and Superconductivity of Ba2Ti2(Fe1−x Cr x )2As4O
Ba2Ti2(Fe1−x Cr x )2As4O (0 ≤ x ≤ 8%) compounds are synthesized by solid-state reaction and their structure and superconductivity are studied with x-ray diffraction, electric resistivity, and magnetization measurements. It is observed that the Cr dopants in the Fe site of Ba2Ti2Fe2As4O expand the lattice constants, but do not cause any structure phase transition. Superconducting transition temperature T c of the Ba2Ti2(Fe1−x Cr x )2As4O is found monotonically depressed with Cr doping level at an average depression rate of ΔT c /Cr − 1% = − 2.6 K. Meanwhile, the superconducting volume fraction is also significantly reduced, and the low-temperature resistivity is enhanced. It is believed that the Cr dopants work as pair-breaking impurities, which take responsibility for the depression of superconductivity in the system.
KeywordsSolid-state reaction Iron-based pnictide Electrical resistivity Magnetic magnetization Superconductivity
The authors are grateful for the helpful discussion with Miss L. Zhao.
The authors are grateful for the financial support of the National Natural Science Foundation of China (Grant No. 51377138). C. Ke is also grateful for the financial support of the Li Jinsheng Scholarship of Superconductivity and New Energy R&D Center.
- 12.Ma, J.Z., van Roekeghem, A., Richard, P., Liu, Z.H., Miao, H., Zeng, L.K., Xu, N., Shi, M., Cao, C., He, J.B., Chen, G.F., Sun, Y.L., Cao, G.H., Wang, S.C., Biermann, S., Qian, T., Ding, H.: Correlation-induced self-doping in the iron-pnictide superconductor Ba2Ti2Fe2As4O. Phys. Rev. Lett. 113, 266407 (2014)ADSCrossRefGoogle Scholar
- 13.Yoon, S.J., Seo, Y.S., Lee, S.B., Weiss, J.D., Jiang, J.Y., Oh, M.J., Lee, J.M., Seo, S.H., Jo, Y.J., Hellstrom, E.E., Hwang, J.S., Lee, S.H.: Structural, electro-magnetic, and optical properties of Ba(fe,Ni)2As2 single-crystal thin film. Supercond. Sci. Technol. 30, 035001 (2017)ADSCrossRefGoogle Scholar
- 15.Uhoya, W.O., Montgomery, J.M., Samudrala, G.K., Tsoi, G.M., Vohra, Y.K., Weir, S.T., Sefat, A.S.: High-pressure structural phase transitions in chromium doped BaFe2As2. J. Phys.: Conf. Series 377, 012016 (2012)Google Scholar
- 17.Ablimit, A., Sun, Y.L., Jiang, H., Bao, J.K., Zhai, H.F., Tang, Z.T., Liu, Y., Wang, Z.C., Feng, C.M., Cao, G.H.: Synthesis, crystal structure and physical properties of a new oxypnictide Ba2Ti2Cr2As4O containing [Ti2As2O]2− and [Cr2As2]2− layers. J. Alloys Compd. 694, 1149–1153 (2017)CrossRefGoogle Scholar
- 24.Marty, K., Christianson, A.D., Wang, C.H., Matsuda, M., Cao, H., VanBebber, L.H., Zarestky, J.L., Singh, D.J., Sefat, A.S., Lumsden, M.D.: Competing magnetic ground states in nonsuperconducting Ba(Fe1−xCrx)2As2 as seen via neutron diffraction. Phys. Rev. B 83, 060509(R) (2011)ADSCrossRefGoogle Scholar