Scanning tunneling spectroscopy study of c-axis proximity effect in epitaxial bilayer manganite/cuprate thin films

Abstract

Recent experimental studies have indicated novel superconducting proximity effects in thin-film heterostructures comprising ferromagnetic manganites and superconducting cuprates. To look for such effects microscopically, we performed scanning tunneling spectroscopy on La${}_{2/3}$Ca${}_{1/3}$MnO${}_3$/YBa${}_2$Cu${}_3$O${}_{7-\delta }$ (LCMO/YBCO) bilayer thin films. $\text{c}$-axis oriented films of varying thickness were grown on SrTiO${}_3$ substrates using pulsed laser-ablated deposition. Heteroepitaxiality of the films was confirmed by cross-sectional transmission electron microscopy. Tunneling spectra were measured at 4.2 K, and analyzed for signatures of a pairing gap on the LCMO layer. For bilayer samples with LCMO thickness down to 5nm, asymmetric conductance spectra characteristic of single-layer LCMO films were observed, showing no clear gap structures. These observations are consistent with a very short-range proximity effect involving spin-singlet pairs, and difficult to reconcile with longer-range proximity scenarios involving spin-triplet pairs.

5 pages, 3 figures

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Cited by in corpus (9)

• Topological superconductivity and Majorana fermions in hybrid structures involving cuprate high-T_c superconductors
• Robustness of Spin-Triplet Pairing and Singlet-Triplet Pairing Crossover in Superconductor/Ferromagnet Hybrids
• Attenuation of superconductivity in manganite/cuprate heterostructures by epitaxially-induced CuO intergrowths
• Superconductor to Mott insulator transition in YBa${}_2$Cu${}_3$O${}_7$/LaCaMnO${}_3$ heterostructures
• Linear dichroism infrared resonance in over-, under-, and optimally-doped cuprate superconductors
• Superconductivity-driven magnetization modulation in YBa2Cu3O7-δ /SrTiO3/La0.67Sr0.33MnO3 heterostructures
• Modeling Tunneling for the Unconventional Superconducting Proximity Effect
• Giant shot noise in superconductor/ferromagnet junctions with orbital-symmetry-controlled spin-orbit coupling
• Andreev Reflection without Fermi surface alignment in High T${}_c$-Topological heterostructures