Superconducting transition of GdBa2Cu3O7-x/La0.7A0.3MnO3 (A=Sr and Ca) bilayers governed by tunable interlayer structural coupling

• Published in: Journal of alloys and compounds Vol. 1008; p. 176699
• Main Authors: Oh, Jun-Yung, Putra, Rico P., Kang, Byeongwon
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2024
• Subjects: Bond stiffness; EXAFS; GdBCO; LCMO; LSMO; Structural coupling; Bond stiffness; LSMO; LCMO; Structural coupling; EXAFS; GdBCO
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.176699

Bilayers composed of high-Tc cuprate superconductors (HTS) with manganites have garnered significant attention due to the complex interaction between two layers, leading to competition among various ordering phenomena. When HTS and manganties are interfaced, new functionalities can emerge that are absent in the individual components. Notably, epitaxial strain can alter crystal structures and electronic states, significantly impacting superconductivity in HTS/manganite heterostructures. In this study, we analyze the superconducting and ferromagnetic behaviors of GdBa2Cu3O7-x(GdBCO)/La0.7A0.3MnO3(LAMO, where A=Sr and Ca) bilayers, maintain a constant GdBCO thickness of 500 nm while varying the LAMO thickness from 25 to 100 nm. We focus on the local structural correlations between the two layers. Temperature-dependent EXAFS spectra were systematically measured at the Cu and Mn K-edges to investigate the local atomic structures of both layers across the superconducting transition temperature (Tc). Our spectroscopic measurements reveal distinct conformations of the MnO6 octahedra near Tc, which are absent in single-layer LSMO, indicating structural coupling between the layers. Additionally, our magnetization studies show a strong relationship between the structural coupling, magnetic anisotropy (MA), and the superconducting transition of the GdBCO/LAMO bilayers. The additional distortion of the MnO6 octahedra in the GdBCO/LAMO bilayer, likely stemming from structural coupling, may account for the changes in the superconducting transition associated with magnetic anisotropy. This modification of structural coupling can be controlled by adjusting the LAMO thickness, yet it remains highly dependent on the bond geometry of LAMO. The Mn-O bond in LCMO is stiffer than in LSMO, resulting in a smaller change in structural coupling with varying thickness in LCMO compared to LSMO. The disparity in structural coupling directly impacts the magnetic properties of the LAMO layer and subsequently influences the superconducting property ΔTc. Our findings highlight the significance of structural coupling as a critical factor affecting the superconductivity of GdBCO/LAMO bilayers. Furthermore, this study provide foundational insight for designing various applications, such as magnetic sensors and spintronic devices, by enhancing our understanding of local dynamics at the interface between ferromagnets and superconductors. •GdBCO/LAMO (A = Sr, Ca) bilayers with different thickness of LAMO were deposited.•Structural coupling exists between Cu-O bond in GdBCO and Mn-O bond in LAMO.•Structural coupling is found to depend on stiffness of Mn-O bond.•Superconducting transition of GdBCO depends on magnetic property of LAMO.