title: Selective interlayer ferromagnetic coupling between the Cu spins in YBa2Cu3O7-x grown on top of La0.7Ca0.3MnO3.
abstract: Studies to date on ferromagnet/d-wave superconductor heterostructures focus mainly on the effects at or near the interfaces while the response of bulk properties to heterostructuring is overlooked. Here we use resonant soft x-ray scattering spectroscopy to reveal a novel c-axis ferromagnetic coupling between the in-plane Cu spins in YBa2Cu3O7-x (YBCO) superconductor when it is grown on top of ferromagnetic La0.7Ca0.3MnO3 (LCMO) manganite layer. This coupling, present in both normal and superconducting states of YBCO, is sensitive to the interfacial termination such that it is only observed in bilayers with MnO2 but not with La0.7Ca0.3O interfacial termination. Such contrasting behaviors, we propose, are due to distinct energetic of CuO chain and CuO2 plane at the La0.7Ca0.3O and MnO2 terminated interfaces respectively, therefore influencing the transfer of spin-polarized electrons from manganite to cuprate differently. Our findings suggest that the superconducting/ferromagnetic bilayers with proper interfacial engineering can be good candidates for searching the theorized Fulde-Ferrel-Larkin-Ovchinnikov (FFLO) state in cuprates and studying the competing quantum orders in highly correlated electron systems.
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.|Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.|MAX IV Laboratory, Lund University, P. O. Box 118, 22100 Lund, Sweden.
authors.forename: S W
authors.initials: SW
authors.lastname: Huang
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.|Department of Physics, New York University, New York, 10003, USA.|Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA.
authors.forename: L Andrew
authors.initials: LA
authors.lastname: Wray
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.|Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Horng-Tay
authors.initials: HT
authors.lastname: Jeng
authors.affiliation: Institute of Physics, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: V T
authors.initials: VT
authors.lastname: Tra
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: J M
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Langner
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: J M
authors.initials: JM
authors.lastname: Chen
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: S
authors.initials: S
authors.lastname: Roy
authors.affiliation: Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan.
authors.forename: Y H
authors.initials: YH
authors.lastname: Chu
authors.affiliation: Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: R W
authors.initials: RW
authors.lastname: Schoenlein
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Y-D
authors.initials: YD
authors.lastname: Chuang
authors.affiliation: Institute of Physics, National Chiao Tung University, Hsinchu 30010, Taiwan.|Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Lin