Open Access

ABSTRACT

Ab-initio Insights into the Single Superconducting CaCuO2/SrTiO3 Interface

by Jinjin Cao, Xiaofan Gou*

1 College of Mechanics and Materials, Hohai University, Nanjing, 211100, China.

* Corresponding Author: Xiaofan Gou. E-mail: .

The International Conference on Computational & Experimental Engineering and Sciences 2019, 22(1), 117-117. https://doi.org/10.32604/icces.2019.05484

Abstract

In order to achieve higher superconducting transition temperature (T_c), the low dimensional superconducting systems have been the interest in recent years. The recent improved film deposition techniques have allowed the realization of the artificial heterostructures, with atomically flat interfaces. The relatively higher T_c was achieved in these heterosturcture interfaces, which is not present in the single constituent. For instance, the quasi-two-dimensional (quasi-2D) superconductivity was found in the FeSe/SrTiO₃ interface with T_c as high as 109 K, which is rather larger than that in the bulk FeSe with T_c of 8 K. Such similar phenomenon also appears in the other quasi-2D system, CaCuO₂/SrTiO₃ heterostructure interface with T_c as high as 55 K, where the bulk CaCuO₂ is an antiferromagnetic insulator. For the former one FeSe/SrTiO3, lots of reports show that the charge transfer and the interface-enhanced electron-phonon coupling contribute the majority of the enhanced T_c. However, for the latter one CaCuO₂/SrTiO₃, only the experiments infer that the charge transfer should be one of the major determining factors, and there is no available theoretical result so far. As the CaCuO₂/SrTiO₃ heterostructure can be regarded as another form of cuprate superconductor, then the theoretical investigations should help to forward understanding the mechanism of superconductivity in cuprate and provide an insight into the exploration of new superconductors by interface engineering. Motivated by further uncovering the interface-induced superconductivity in CaCuO₂/SrTiO₃, and inspired by the reports on FeSe/SrTiO₃, we performed ab-initio calculations to study the charge doping effect on the atomic and electronic band structures and electron-phonon interactions in this CaCuO₂/SrTiO₃ interface. The microstructure in this interface is identified with the stacking sequence SrO-TiO₂-CaO_x-CuO₂, according to the criterion of lowest energy. On the basis of the determined microstructure of interface, the roles of charge transfer and electron-phonon interactions were also identified in determining the interface-induced superconductivity in CaCuO₂/SrTiO₃.

---