Interfacial Superconductivity Achieved in Parent AEFe₂As₂ (AE = Ca, Sr, Ba) by a Simple and Realistic Annealing Route

Abstract

Materials with interfaces often exhibit extraordinary phenomena exemplified by rich physics, such as high-temperature superconductivity and enhanced electronic correlations. However, demonstrations of confined interfaces to date have involved intensive effort and fortuity, and no simple path is consistently available. Here, we report the achievement of interfacial superconductivity in the nonsuperconducting parent compounds AEFe 2 As 2 , where AE = Ca, Sr, or Ba, by simple subsequent annealing of the as-grown samples in an atmosphere of As, P, or Sb. Our results indicate that the superconductivity originates from electron transfer at the interface of the hybrid van der Waals heterostructures, consistent with the two-dimensional superconducting transition observed. The observations suggest a common origin of interfaces for the nonbulk superconductivity previously reported in the AEFe 2 As 2 compound family and provide insight for the further exploration of interfacial superconductivity.

Impact of Correlated Disorder on Surface Superconductivity: Revealing the Robustness of the Surface Ordering Effect

“…Recent developments within density functional theory predicted a significant enhancement of the superconducting transition temperature ( T c ) at the surfaces of Ca n B n +1 C n +1 films, increasing it from 8 K for bulk CaBC to 90 K . It is interesting to note that surface superconductivity has also been observed in nonsuperconductive parent compounds, while interfacial superconductivity can emerge when suitable partner compounds are brought into contact with insulating materials. − Of particular note is the high- T c superconductivity that occurs at the interface between metallic and insulating copper oxides . Reports even suggest an induced superconductivity at the surfaces and interfaces of topological insulators.…”

Effect of Material-Dependent Boundaries on the Interference Induced Enhancement of the Surface Superconductivity Temperature

“…It was discovered that surface superconductivity can manifest itself in non-superconductive parent compounds . Also, interface superconductivity appears in the non-superconductive parent compounds or can even appear in some insulating materials once they are brought into contact with suitable partner compounds. − Even the high- T c superconductivity was observed at the interface of metallic and insulating copper oxides . Recent experiments with FeSe few-layer films grown on SrTiO 3 suggest that interface effects can be used as a means to achieve superconducting critical temperature T c up to 109 K .…”