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@ARTICLE{Rodrigo:877690,
      author       = {Rodrigo, Rebecca and Faley, M. I. and Dunin-Borkowski,
                      Rafal},
      title        = {{N}ano{SQUID}s based on {N}b nanobridges},
      journal      = {Journal of physics / Conference Series},
      volume       = {1559},
      number       = {1},
      issn         = {1742-6588},
      address      = {Bristol},
      publisher    = {IOP Publ.87703},
      reportid     = {FZJ-2020-02400},
      pages        = {012011},
      year         = {2020},
      abstract     = {Atomic-scale imaging of interfacial polarizationin
                      cuprate-titanate heterostructuresCite as: Appl. Phys. Lett.
                      116, 251603 (2020); doi: 10.1063/5.0011081Submitted: 17
                      April 2020 . Accepted: 7 June 2020 .Published Online: 23
                      June 2020Shao-Bo Mi,1,a) Tian Yao,1 Shao-Dong Cheng,1,2
                      Micheal I. Faley,3 Ulrich Poppe,3 Lu Lu,1,2 Dawei
                      Wang,1,2and Chun-Lin Jia1,2,3AFFILIATIONS1State Key
                      Laboratory for Mechanical Behavior of Materials, Xi’an
                      Jiaotong University, Xi’an 710049, China2School of
                      Microelectronics, Xi’an Jiaotong University, Xi’an
                      710049, China3Ernst Ruska Centre for Microscopy and
                      Spectroscopy with Electrons and Peter Gr€unberg
                      Institute,ForschungszentrumJ€ulich, D-52425 J€ulich,
                      Germanya)Author to whom correspondence should be addressed:
                      shaobo.mi@xjtu.edu.cnABSTRACTThe interfaces in oxide
                      heterostructures that bring novel physical phenomena and
                      functionalities have attracted great attention infundamental
                      research and device applications. For uncovering
                      structure–property relationships of oxide
                      heterostructures, direct evidence ofthe atomic-scale
                      structure of heterointerfaces is highly desired. Here, we
                      report on studying the structure of interfaces between
                      YBa2Cu3O7-dthin films and SrTiO3 substrates by means of
                      aberration-corrected ultrahigh-resolution electron
                      microscopy. Employing advanced imagingand spectroscopic
                      techniques, shifts of atoms at the interface away from the
                      regular lattice sites are measured, leading to the
                      interfacial polarity.The local polarization induced by the
                      atomic shifts directs toward the cuprate films and is
                      estimated to be about 36.1 lC/cm2. Theobserved interfacial
                      polar layer is understood by the special atomic
                      configuration across the interface, which could modulate the
                      electricalproperties in superconducting devices that are
                      based on the ferroelectric/superconductor
                      heterosystems.Published under license by AIP Publishing.
                      https://doi.org/10.1063/5.0011081Heterostructures of
                      perovskite-based oxide materials haveattracted extensive
                      attention from both fundamental research andtechnological
                      applications because of their variety of fascinating
                      physicalproperties.1,2 It has been demonstrated that
                      interfaces in thedesigned heterostructures have striking
                      properties, which do not existin either of the constituent
                      bulk materials, e.g., 2D electron gas at theLaAlO3/SrTiO3
                      (LAO/STO) interface.3,4 In addition, the functionalitiesof
                      the perovskite-based oxide epitaxial layers can be modulated
                      bythe field effect arising from the adjacent layers or/and
                      the interfacecoupling in heterostructures (e.g., proximity
                      effects in superconductor–ferromagnet
                      heterostructures).5–7 Among the
                      perovskite-basedheterostructures, strongly
                      electron-correlated materials are of essentialimportance due
                      to their applications in superconducting
                      field-effectdevices, e.g., high-temperature superconducting
                      (HTS) ultrathin filmsgrown on insulating STO
                      substrates.8–10 In these heterostructures, thecritical
                      temperature (Tc) and phase transitions of the HTS
                      cupratefilms can be tuned by an external electric field
                      without involvingchemical and crystalline modulation of the
                      materials. Also, it wasreported that the Tc of the ultrathin
                      HTS films can be shifted by thecharge carriers, which are
                      injected by the dielectric gate polarizationunder an applied
                      electric field and thus leading to a suppression
                      ofsuperconductivity in the ultrathin HTS films.11–14The
                      Thomas–Fermi screening length (kTF) of YBa2Cu3O7-d(YBCO)
                      is on the order of 1nm.15 Therefore, the interface
                      couplingbetween the dielectric gate and the YBCO films has
                      importanteffect on shifting Tc of the ultrathin YBCO films.
                      In particular, theinterfacial polarity of the
                      heterostructures has been expected tochange the doping level
                      and thus to affect the superconductivity ofthe
                      unit-cell-thick HTS cuprate films.16 Although the
                      experimentaland theoretical investigations have been
                      performed on studyingHTS heterostructures,9,10,17–19 the
                      interfacial atomic arrangementof superconducting/insulating
                      heterostructures, including reconstructions,relaxations,
                      interatomic mixing, and distortions, is necessaryto be
                      clarified for a deep insight into the mechanismsbehind the
                      experimentally measured interface-related properties.In this
                      work, we provide the atomic-scale interface structure
                      ofYBCO/STO(001) obtained by using high-resolution imaging
                      andspectroscopic techniques of aberration-corrected
                      transmissionelectron microscopy (TEM) and scanning
                      transmission electronmicroscopy (STEM).Appl. Phys. Lett.
                      116, 251603 (2020); doi: 10.1063/5.0011081 116,
                      251603-1Published under license by AIP PublishingApplied
                      Physics Letters ARTICLE scitation.org/journal/apl},
      cin          = {ER-C-1 / PGI-5},
      ddc          = {530},
      cid          = {I:(DE-Juel1)ER-C-1-20170209 / I:(DE-Juel1)PGI-5-20110106},
      pnm          = {144 - Controlling Collective States (POF3-144) / 143 -
                      Controlling Configuration-Based Phenomena (POF3-143)},
      pid          = {G:(DE-HGF)POF3-144 / G:(DE-HGF)POF3-143},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000558737600011},
      doi          = {10.1088/1742-6596/1559/1/012011},
      url          = {https://juser.fz-juelich.de/record/877690},
}