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Giant anisotropy in superconducting single crystals of CsCa$_2$Fe$_4$As$_4$F$_2$
- Source :
- Phys. Rev. B 99, 144501 (2019)
- Publication Year :
- 2018
-
Abstract
- CsCa$_2$Fe$_4$As$_4$F$_2$ is a newly discovered iron-based superconductor with $T_\mathrm{c}\sim$ 30 K containing double Fe$_2$As$_2$ layers that are separated by insulating Ca$_2$F$_2$ spacer layers. Here we report the transport and magnetization measurements on CsCa$_2$Fe$_4$As$_4$F$_2$ single crystals grown for the first time using the self flux of CsAs. We observed a huge resistivity anisotropy $\rho_c(T)/\rho_{ab}(T)$, which increases with decreasing temperature, from 750 at 300 K to 3150 at 32 K. The $\rho_c(T)$ data exhibit a non-metallic behavior above $\sim$140 K, suggesting an incoherent electronic state at high temperatures due to the dimension crossover. The superconducting onset transition temperature in $\rho_{ab}$ is 0.7 K higher than that in $\rho_c$, suggesting two-dimensional (2D) superconducting fluctuations. The lower and upper critical fields also show an exceptional anisotropy among iron-based superconductors. The $H_{c1}^\bot(T)$ data are well fitted using the model with two $s$-wave-like superconducting gaps, $\Delta_1(0)=6.75$ meV and $\Delta_2(0)=2.32$ meV. The inter-plane coherence length $\xi_c(0)$ is $3.6$ \AA, remarkably smaller than the distance between conducting layers (8.6 \AA), consolidating the 2D nature in the title material.<br />Comment: 8 pages, 5 figures, 1 Table
- Subjects :
- Condensed Matter - Superconductivity
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 99, 144501 (2019)
- Publication Type :
- Report
- Accession number :
- edsarx.1811.05706
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.99.144501