Anisotropy induced vortex lattice rearrangement in CaKFe${}_4$As${}_4$

Abstract

The magnetic penetration depth anisotropy ${\gamma }_{\lambda }={\lambda }_c/{\lambda }_{ab}$ (${\lambda }_{ab}$ and ${\lambda }_c$ are the in-plane and the out-of-plane components of the magnetic penetration depth) in a CaKFe${}_4$As${}_4$ single crystal sample (the critical temperature $T_{\mathrm{c}}\simeq 35$ K) was studied by means of muon-spin rotation ($\mu$SR). ${\gamma }_{\lambda }$ is almost temperature independent for $T\lesssim 20$ K (${\gamma }_{\lambda }\simeq 1.9$) and it reaches $\simeq 3.0$ by approaching $T_{\mathrm{c}}$. The change of ${\gamma }_{\lambda }$ induces the corresponding rearrangement of the flux line lattice (FLL), which is clearly detected via enhanced distortions of the FLL $\mu$SR response. Comparison of ${\gamma }_{\lambda }$ with the anisotropy of the upper critical field (${\gamma }_{H_{c2}}$) studied in Phys. Rev B {\bf 94}, 064501 (2016), reveals that ${\gamma }_{\lambda }$ is systematically higher than ${\gamma }_{H_{c2}}$ at low-temperatures and approaches ${\gamma }_{H_{c2}}$ for $T\to T_{\mathrm{c}}$. The anisotropic properties of $\lambda$ are explained by the multi-gap nature of superconductivity in CaKFe${}_4$As${}_4$ and are caused by anisotropic contributions of various bands to the in-plane and the out-of-plane components of the superfluid density.

6 pages, 4 figures

References in corpus (10)

• Momentum-resolved superconducting gap in the bulk of Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ from combined ARPES and $\mu$SR measurements
• Muon-spin rotation studies of SmFeAsO_0.85 and NdFeAsO_0.85 superconductors
• Universal observation of multiple order parameters in cuprate superconductors
• Comparison of different methods for analyzing $\mu$SR line shapes in the vortex state of type-II superconductors
• Anisotropy of superconducting single crystal SmFeAsO_(0.8)F_(0.2) studied by torque magnetometry
• Evidence for two distinct anisotropies in the oxypnictide superconductors SmFeAsO_(0.8)F_(0.2) and NdFeAsO_(0.8)F_(0.2)
• Electronic properties, low-energy Hamiltonian and superconducting instabilities in CaKFe${}_4$As${}_4$
• Evidence for competition between the superconducting and the pseudogap state in (BiPb)_2(SrLa)_2CuO_{6+δ} from muon-spin rotation experiments
• Muons as Local Probes of Three-body Correlations in the Mixed State of Type-II Superconductors
• Low anisotropy of the upper critical field in a strongly anisotropic layered cuprate: Evidence for paramagnetically limited superconductivity

Cited by in corpus (4)

• The single- vs. two-gap scenario: the specific heat and the thermodynamic critical field of BeAu superconductor
• Muon spin rotation study of type-I superconductivity: elemental $\beta -$Sn
• Superconductivity and magnetic and transport properties of single-crystalline CaK(Fe${}_{1-x}$Cr${}_x$)${}_4$As${}_4$
• Superconductivity of Co-Doped CaKFe4As4 Investigated via Point-Contact Spectroscopy and London Penetration Depth Measurements