Abstract
Interface-related phenomena have great potential to control the superconducting state in Fe-based superconductors. We propose a comprehensive classification of Fe-pnictide heterointerfaces based on electrostatic principles that allow the prediction of the interface microstructure, in particular, distinguishing between clean heterointerfaces and the formation of interfacial layers. The concept was successfully tested on a novel LnOFeAs/BaFe2As2 (Ln = La, Sm) Fe-pnictide heterostructure. With the addition of different cations/anions, it is possible to produce clean interfaces or interfacial layers. The impact of the microstructure on superconductivity in the Fe-pnictide heterostructures is discussed.
Highlights
The design and study of functional interfaces has become increasingly important in the interdisciplinary fields of materials science, condensed matter, and applied physics
In the context of Fe-based superconductors, the controlled engineering of novel interfaces is starting to play a key role. It helps to elucidate the interplay between charge, spin, and lattice degrees of freedom that might be relevant for high-temperature superconductivity; on the other hand, it is required to advance the potential for device applications
The results demonstrate the proof-of-principle: clean and smooth interfaces were obtained for the undoped (Fig. 2a, d, g) and Co2+-substituted cases (Fig. 2b, e), whereas an interface layer (IFL) of higher roughness was formed with excess O2− (Fig. 2c, f, h)
Summary
The design and study of functional interfaces has become increasingly important in the interdisciplinary fields of materials science, condensed matter, and applied physics. The heterointerface between a Fechalcogenide and a perovskite oxide in monolayer (ML-) FeSe/SrTiO3 demonstrated an ability to host hightemperature superconductivity in the range of 40–75 K.1–3. This transition temperature, which exceeds the value of its bulk counterpart by almost one order of magnitude, is believed to be the result of a cooperative (interfacial) Cooper pairing interaction.[4]. While interface engineering of ML-FeSe/SrTiO3 has attracted much attention and established protocols have been worked out,[5] analogous interfacial control for Fepnictide superconductors is less developed because generalized engineering concepts are lacking. Fepnictide heterointerfaces are found with an additional reaction layer that complicates interfacial superconductivity or junction design. We show that interface-related phenomena in Fe-based superconductors hold exceptional promise for their further design and exploration once their microstructure is understood in detail
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