In a triclinic iron pnictide superconductor, a spin resonance precursor, Nernst signal, and NMR density-of-states reduction all point to preformed Cooper pairs persisting to T* = 45 K, above Tc = 30 K.
Antiferromagnetic order in Ca$_{10}$(Pt$_3$As$_8$)(Fe$_2$As$_2$)$_5$ observed by $^{75}$As NMR
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abstract
$^{75}$As nuclear magnetic resonance (NMR) measurements carried out on underdoped, non-superconducting Ca$_{10}$(Pt$_3$As$_8$)(Fe$_2$As$_2$)$_5$ reveal physical properties that are similar but not identical to the 122 superconductor parent compounds such as BaFe$_2$As$_2$. Results from the single crystal study indicate a phase transition to an antiferromagnetic (AF) state on cooling through T~100K, albeit nonuniformly. Specifically, the NMR lineshape reflects the presence of staggered hyperfine fields on the As sites associated with a striped AF order. The variation of the internal hyperfine field with temperature suggests that the phase transition to the AF state is discontinuous, and therefore likely coincident with the structural transition inferred from transport experiments.
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cond-mat.supr-con 1years
2025 1verdicts
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Preformed Cooper Pairs in a Triclinic Iron Pnictide Superconductor
In a triclinic iron pnictide superconductor, a spin resonance precursor, Nernst signal, and NMR density-of-states reduction all point to preformed Cooper pairs persisting to T* = 45 K, above Tc = 30 K.