Two-dimensional magnetism in the pnictide superconductor parent material SrFeAsF probed by muon-spin relaxation

Physical review. B, Condensed matter (Impact Factor: 3.66). 11/2008; 79(6). DOI: 10.1103/PhysRevB.79.060402
Source: arXiv


We report muon-spin relaxation measurements on SrFeAsF, which is the parent compound of a newly discovered iron-arsenic-fluoride based series of superconducting materials. We find that this material has very similar magnetic properties to LaFeAsO, such as separated magnetic and structural transitions (TN = 120 K, Ts = 175 K), contrasting with SrFe2As2 where they are coincident. The muon oscillation frequencies fall away very sharply at TN, which suggests that the magnetic exchange between the layers is weaker than in comparable oxypnictide compounds. This is consistent with our specific heat measurements, which find that the entropy change S = 0.05 J/mol/K largely occurs at the structural transition and there is no anomaly at TN. Comment: 4 pages, 3 figures

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Available from: I. Franke, Oct 03, 2015
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    ABSTRACT: We investigate structural, magnetic, and electronic properties of SrFeAsF as a new parent for superconductors using state-of-the-art density-functional theory method. Calculated results show that striped antiferromagnetic order is the magnetic ground state in the Fe layer and interlayer magnetic interaction is tiny. Calculated As and Sr positions are in agreement with experiment. There are only two uniaxially-dispersed bands near the Fermi level. The valent charge is mainly in the Fe and F layers, and the magnetic moment is confined to the Fe atoms. Inter-Fe-spin couplings is due to superexchange through As atoms. These are useful to understanding the SrFeAsF and should have helpful implications to doped samples.
    EPL (Europhysics Letters) 11/2008; 85(6):67009. DOI:10.1209/0295-5075/85/67009 · 2.10 Impact Factor
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    ABSTRACT: In this short review, we attempt to give a comprehensive discussion of studies performed to date by muon-spin spectroscopy (more precisely the relaxation and rotation technique, also know as μSR) on the recently discovered layered iron-based superconductors. On one side, μSR has been used to characterize the magnetic state of different families of layered iron-based systems. Similarly the subtle interplay of the magnetic state and the structural transition present in some families has been investigated. We will also discuss the information provided by this technique on the interaction between the magnetic state and the superconducting phase. Finally the μSR technique has been used to investigate the magnetic penetration depth of the superconducting ground state. The study of its absolute value, temperature and magnetic field dependence provides crucial tests for investigating possible unconventional superconducting states in such systems.
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    ABSTRACT: In this review, the authors present a summary of experimental reports on newly discovered iron-based superconductors as they were known at the end of 2008. At the same time, this paper is intended to be useful for experimenters to know the current status of these superconductors. The authors introduce experimental results that reveal basic physical properties in the normal and superconducting states. The similarities and differences between iron-pnictide superconductors and other unconventional superconductors are also discussed. Comment: 20 pages, 32 figures. Open select
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