Control of Epitaxial BaFe₂As₂ Atomic Configurations with Substrate Surface Terminations

Abstract

Atomic layer controlled growth of epitaxial thin films of unconventional superconductors opens the opportunity to discover novel high temperature superconductors. For instance, the interfacial atomic configurations may play an important role in superconducting behavior of monolayer FeSe on SrTiO and other Fe-based superconducting thin films. Here, we demonstrate a selective control of the atomic configurations in Co-doped BaFeAs epitaxial thin films and its strong influence on superconducting transition temperatures by manipulating surface termination of (001) SrTiO substrates. In a combination of first-principles calculations and high-resolution scanning transmission electron microscopy imaging, we show that Co-doped BaFeAs on TiO-terminated SrTiO is a tetragonal structure with an atomically sharp interface and with an initial Ba layer. In contrast, Co-doped BaFeAs on SrO-terminated SrTiO has a monoclinic distortion and a BaFeO initial layer. Furthermore, the superconducting transition temperature of Co-doped BaFeAs ultrathin films on TiO-terminated SrTiO is significantly higher than that on SrO-terminated SrTiO, which we attribute to shaper interfaces with no lattice distortions. This study allows the design of the interfacial atomic configurations and the effects of the interface on superconductivity in Fe-based superconductors.

In-plane rotation and transition from rectification to bipolar resistive switching in ZnO/SrTiO3:Nb heterojunctions by substrate pretreatment

“…[1][2][3] Due to a small lattice mismatch, SrTiO 3 (STO) single crystal is widely used as a substrate for various functional oxide lms including ZnO. [4][5][6] The STO substrate pretreatment was found to signicantly affect the growth behavior and electrical transport property of thin lms. 7,8 Particularly, a light switchable resistive switching memory is observed in ZnO/(100)NSTO heterojunctions, 9 a regular rectication is observed in ZnO/(100)NSTO heterojunctions, 10 an attendant behavior of bipolar resistance switching and negative differential resistance characteristics have been observed in ZnO/(100)NSTO heterojunctions, 8 a magnetic enhanced rectication is observed in ZnO/(100) NSTO heterojunctions, 12 and a magnetic induced bipolar resistance switching is observed in ZnO/(110) heterojunctions.…”

Realization of epitaxial thin films of the superconductor K-doped BaFe2As2

“…An atomic-resolution image is shown in Fig. 2(d), where each atomic column in the [100] direction can be recognized [42,43]. This column arrangement is blurred at grain boundaries owing to misorientation as shown in Fig.…”

Superconductivity in undoped BaFe 2 As 2 by tetrahedral geometry design

“…2D). Previous theoretical calculations on the STO/Ba-122 interface support suppressed intermixing at the bottom interface, as the Ba layer is thermodynamically stable on TiO 2 -terminated STO with an atomically sharp interface (29). In contrast, there are a small number of As and Fe atoms missing in Ba-122 underneath the top interface (red and blue arrows) due to Ti diffusion (purple arrows).…”