Epitaxial Iridate/Cuprate Heterostructures for Proximity Effect Studies

Epitaxial heterostructures of superconducting cuprates and transition-metal perovskites provide a rich playground for the study of novel proximity effects (PE). A prominent example is the heterostructuring of YBa₂Cu₃O_7-δ and half-metallic manganites in thin-film form, which is believed to host spin-triplet odd-frequency pairing with d-wave orbital symmetry [1], although heteroepitaxial strain can also play a role in the observed effects [2]. In this study, we introduce spin-orbit coupling (SOC) into the PE scenario by heterostructuring superconducting YBa₂Cu₃O_7-δ with a semimetallic iridate SrIr_1-xO_3-δ, in an effort to study novel effects that the strong SOC in the iridate may have on the proximity coupling and the proximity-induced pairing state [3]. Our multilayer YBa₂Cu₃O_7-δ/SrIr_1-xO_3-δ heterostructures are epitaxially grown using pulsed laser-ablated deposition, followed by post-annealing with a superoxygenation process [4]. The samples are characterized using x-ray diffraction/reflectometry and scanning transmission electron microscopy. Electrical transport and scanning tunneling spectroscopy measurements are made to look for distinct evidence of novel PE in these iridate/cuprate heterostructures.

[1] D. Sanchez-Manzano et al., Nat. Mater. 21 (2022)

[2] C. Zhang et al., Ceramics International 49 (2023)

[3] T. Yokoyama et al., Phys. Rev. B 74 (2006); M. Eschrig, Rep. Prog. Phys. 78 (2015)

[4] H. Zhang et al., Phys. Rev. Mater. 2 (2018)