Multigap superconductivity in RbCa2Fe4As4F2 investigated using μSR measurements

Journal article

The superconducting properties of the recently discovered high-Tc superconductor RbCa2Fe4As4F2 with double Fe2As2 layers and Tc ≈ 30 K have been investigated using magnetization, heat capacity, transverse-field (TF) and zero-field (ZF) muon-spin rotation/relaxation (μSR) measurements. Low field magnetization and heat capacity (Cp) measurements reveal an onset of bulk superconductivity with Tc ∼ 30.0(4) K, where there is a jump at Tc of ΔCp/Tc = 94.6 (mJ/mole-K2). The temperature dependence of the magnetic penetration depth obtained from transverse-field (TF) μSR is better described by the two-gap s + s and s + d models than the single gap s- or d-wave scenarios. The presence of two superconducting gaps in RbCa2Fe4As4F2 is consistent with the multigap superconductivity observed in other Fe-based superconductors, including ACa2Fe4As4F2 (A = K and Cs). From the TF-μSR study, an in-plane magnetic penetration depth of λab(0) = 231.5(3) nm, a superconducting carrier density ns = 1.29(1) × 1027 m−3, and an effective mass of the carriers of m* = 2.45(1)me are estimated. Zero-field μSR measurements do not reveal clear signs of time reversal symmetry breaking below Tc, but the temperature dependence of the relaxation of the asymmetry between 150 and 1.2 K may indicate the presence of spin-fluctuations.

Authors: Adroja, D; Kirschner, F; Lang, F; Smidman, M; Hillier, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Physical Society of Japan
• Journal: Journal of the Physical Society of Japan
• Volume: 87
• Issue: 12
• Article number: 124705
• Publication date: 2018-11-16
• Acceptance date: 2018-10-04
• DOI: 10.7566/jpsj.87.124705
• EISSN: 1347-4073
• ISSN: 0031-9015
• Language: English