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

Journal article

We report muon-spin relaxation measurements on SrFeAsF, which is the parent compound of an 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 =122 K, Ts =175 K), contrasting with SrFe2 As2 where they are coincident. The muon oscillation frequencies fall away very sharply at TN [β=0.22 (3)], which suggests that the magnetic exchange between the layers is weaker than in comparable oxypnictide compounds. Our specific-heat measurements show that a small but distinct feature occurs at Ts. There is no anomaly evident at TN as is typical for quasi-two-dimensional magnets. The magnetic entropy change between 100 and 185 K is ΔS=0.5 J mol-1 K-1. © 2009 The American Physical Society.

Authors: Baker, P; Franke, I; Lancaster, T; Blundell, S; Kerslake, L

• Publication status: Published
• Journal: Physical Review B
• Volume: 79
• Issue: 6
• Publication date: 2009-02-01
• DOI: 10.1103/PhysRevB.79.060402
• EISSN: 1550-235X
• ISSN: 1098-0121
• Language: English
• Keywords: muon probes; superconducting materials; specific heat; magnetic transitions; strontium compounds; solid-state phase transformations; iron compounds