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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

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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