Disentangling superconducting and magnetic orders in NaFe1-xNixAs using muon spin rotation

Sky C. Cheung, Zurab Guguchia, Benjamin A. Frandsen, Zizhou Gong, Kohtaro Yamakawa, Dalson E. Almeida, Ifeanyi J. Onuorah, Pietro Bonfá, Eduardo Miranda, Weiyi Wang, David W. Tam, Yu Song, Chongde Cao, Yipeng Cai, Alannah M. Hallas, Murray N. Wilson, Timothy J.S. Munsie, Graeme Luke, Bijuan Chen, Guangyang DaiChangqing Jin, Shengli Guo, Fanlong Ning, Rafael M. Fernandes, Roberto De Renzi, Pengcheng Dai, Yasutomo J. Uemura

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Muon spin rotation and relaxation studies have been performed on a "111" family of iron-based superconductors, NaFe1-xNixAs, using single crystalline samples with Ni concentrations x=0, 0.4, 0.6, 1.0, 1.3, and 1.5%. Static magnetic order was characterized by obtaining the temperature and doping dependences of the local ordered magnetic moment size and the volume fraction of the magnetically ordered regions. For x=0 and 0.4%, a transition to a nearly-homogeneous long range magnetically ordered state is observed, while for x 0.4% magnetic order becomes more disordered and is completely suppressed for x=1.5%. The magnetic volume fraction continuously decreases with increasing x. Development of superconductivity in the full volume is inferred from Meissner shielding results for x 0.4%. The combination of magnetic and superconducting volumes implies that a spatially-overlapping coexistence of magnetism and superconductivity spans a large region of the T-x phase diagram for NaFe1-xNixAs. A strong reduction of both the ordered moment size and the volume fraction is observed below the superconducting TC for x=0.6, 1.0, and 1.3%, in contrast to other iron pnictides in which one of these two parameters exhibits a reduction below TC, but not both. The suppression of magnetic order is further enhanced with increased Ni doping, leading to a reentrant nonmagnetic state below TC for x=1.3%. The reentrant behavior indicates an interplay between antiferromagnetism and superconductivity involving competition for the same electrons. These observations are consistent with the sign-changing s± superconducting state, which is expected to appear on the verge of microscopic coexistence and phase separation with magnetism. We also present a universal linear relationship between the local ordered moment size and the antiferromagnetic ordering temperature TN across a variety of iron-based superconductors. We argue that this linear relationship is consistent with an itinerant-electron approach, in which Fermi surface nesting drives antiferromagnetic ordering. In studies of superconducting properties, we find that the T=0 limit of superfluid density follows the linear trend observed in underdoped cuprates when plotted against TC. This paper also includes a detailed theoretical prediction of the muon stopping sites and provides comparisons with experimental results.

Original languageEnglish (US)
Article number224508
JournalPhysical Review B
Volume97
Issue number22
DOIs
StatePublished - Jun 12 2018

Bibliographical note

Funding Information:
The experiments were performed at TRIUMF in Vancouver, Canada and at the Swiss Muon Source () at Paul Scherrer Insitute (PSI) in Villigen, Switzerland. The authors sincerely thank the TRIUMF Center for Material and Molecular Science staff and the PSI Bulk Group for invaluable technical support with experiments. Work at the Department of Physics of Columbia University is supported by US NSF DMR-1436095 (DMREF) and NSF DMR-1610633. Z.G. gratefully acknowledges the financial support by the Swiss National Science Foundation (SNF fellowships P2ZHP2-161980 and P300P2-177832). Work at Columbia, TRIUMF, PSI, and IOP-Beijing has been supported by the REIMEI project funding from the Japan Atomic Energy Agency, and by the support from the Friends of Tokyo University Inc (FUTI). E.M. is supported by CNPq (Grant No. 304311/2010-3). P.B. acknowledges computing resources provided by STFC Scientific Computing Department's SCARF cluster. R.D.R. acknowledges funding by H2020 Research Infrastructures under Grant Agreement No. 654000. This work was supported by the computational node hours granted from the Swiss National Supercomputing Centre (CSCS) under project ID sm07. R.M.F. is supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0012336. C.D.C. acknowledges financial support by the National Natural Science Foundation of China Grant No. 51471135, the National Key Research and Development Program of China under Contract No. 2016YFB1100101, and Shaanxi International Cooperation Program. Works at IOPCAS are supported by NSF and MOST of China through Research Projects as well as by CAS External Cooperation Program of BIC (112111KYS820150017). The Ni-doped NaFeAs single crystal growth efforts at Rice University are supported by DOE, BES, DE-SC0012311, and by the Robert A. Welch Foundation Grant No. C-1839 (P.D.). The present work is a part of the Ph.D. thesis of S.C.C. submitted to and defended at Columbia University in August 2017.

Funding Information:
Work at the Department of Physics of Columbia University is supported by US NSF DMR-1436095 (DMREF) and NSF DMR-1610633. Z.G. gratefully acknowledges the financial support by the Swiss National Science Foundation (SNF fellowships P2ZHP2-161980 and P300P2-177832). Work at Columbia, TRIUMF, PSI, and IOP-Beijing has been supported by the REIMEI project funding from the Japan Atomic Energy Agency, and by the support from the Friends of Tokyo University Inc (FUTI). E.M. is supported by CNPq (Grant No. 304311/2010-3). P.B. acknowledges computing resources provided by STFC Scientific Computing Department's SCARF cluster. R.D.R. acknowledges funding by H2020 Research Infrastructures under Grant Agreement No. 654000. This work was supported by the computational node hours granted from the Swiss National Supercomputing Centre (CSCS) under project ID sm07. R.M.F. is supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Award No. DE-SC0012336. C.D.C. acknowledges financial support by the National Natural Science Foundation of China Grant No. 51471135, the National Key Research and Development Program of China under Contract No. 2016YFB1100101, and Shaanxi International Cooperation Program. Works at IOPCAS are supported by NSF and MOST of China through Research Projects as well as by CAS External Cooperation Program of BIC (112111KYS820150017). The Ni-doped NaFeAs single crystal growth efforts at Rice University are supported by DOE, BES, DE-SC0012311, and by the Robert A. Welch Foundation Grant No. C-1839 (P.D.). The present work is a part of the Ph.D. thesis of S.C.C. submitted to and defended at Columbia University in August 2017.

Publisher Copyright:
© 2018 American Physical Society.

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