Engineering of Fe-pnictide heterointerfaces by electrostatic principles

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.

Recent progress on epitaxial growth of Fe-based superconducting thin films

“…Both LaFeAsO [54] and SmFeAsO [61] were epitaxially grown on MgO (001) and (LaAlO 3 ) 0.7 (Sr 2 TaAlO 6 ) 0.7 (001) [LSAT (001)]. Similarly, SmFe 1−x Co x AsO epitaxial thin films were realized on various substrates using almost the same deposition setup [15,16]. For phase purity and epitaxy, the optimum deposition temperature and substrate were 860 • C and MgO, although a small amount of Sm 2 O 3 was present.…”

“…In this case, cobalt and fluorine co-doping may occur. Later, growth on MgO buffered with Co-doped BaFe 2 As 2 yielded a T c of 13-18 K for SmFe 1−x Co x AsO [16]. Unfortunately, J c measurements have not been reported so far.…”

“…To date, the parent compounds LnFeAsO (Ln = Nd and Sm) have been readily fabricated by molecular beam epitaxy (MBE) and PLD [60,61]. Additionally, epitaxial SmFe 1−x Co x AsO has been grown by PLD [15,16]. For F doping, two methods, namely one-step and two-step growth, have been reported.…”