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Depth-resolved charge reconstruction at the LaNiO3/CaMnO3 interface

  • Author(s): Chandrasena, RU
  • Flint, CL
  • Yang, W
  • Arab, A
  • Nemšák, S
  • Gehlmann, M
  • Özdöl, VB
  • Bisti, F
  • Wijesekara, KD
  • Meyer-Ilse, J
  • Gullikson, E
  • Arenholz, E
  • Ciston, J
  • Schneider, CM
  • Strocov, VN
  • Suzuki, Y
  • Gray, AX
  • et al.
Abstract

© 2018 American Physical Society. Rational design of low-dimensional electronic phenomena at oxide interfaces is currently considered to be one of the most promising schemes for realizing new energy-efficient logic and memory devices. An atomically abrupt interface between paramagnetic LaNiO3 and antiferromagnetic CaMnO3 exhibits interfacial ferromagnetism, which can be tuned via a thickness-dependent metal-insulator transition in LaNiO3. Once fully understood, such emergent functionality could turn this archetypal Mott-interface system into a key building block for the above-mentioned future devices. Here, we use depth-resolved standing-wave photoemission spectroscopy in conjunction with scanning transmission electron microscopy and x-ray absorption spectroscopy, to demonstrate a depth-dependent charge reconstruction at the LaNiO3/CaMnO3 interface. Our measurements reveal an increased concentration of Mn3+ and Ni2+ cations at the interface, which create an electronic environment favorable for the emergence of interfacial ferromagnetism mediated via the Mn4+-Mn3+ ferromagnetic double exchange and Ni2+-O-Mn4+ superexchange mechanisms. Our findings suggest a strategy for designing functional Mott oxide heterostructures by tuning the interfacial cation characteristics via controlled manipulation of thickness, strain, and ionic defect states.

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