Fermi Level shifting, Charge Transfer and Induced Magnetic Coupling at La0.7Ca0.3MnO3/LaNiO3 Interface

Abstract

A large magnetic coupling has been observed at the La0.7Ca0.3MnO3/LaNiO3 (LCMO/LNO) interface. The x-ray photoelectron spectroscopy (XPS) study results show that Fermi level continuously shifted across the LCMO/LNO interface in the interface region. In addition, the charge transfer between Mn and Ni ions of the type Mn3+ − Ni3+ → Mn4+ − Ni2+ with the oxygen vacancies are observed in the interface region. The intrinsic interfacial charge transfer can give rise to itinerant electrons, which results in a “shoulder feature” observed at the low binding energy in the Mn 2p core level spectra. Meanwhile, the orbital reconstruction can be mapped according to the Fermi level position and the charge transfer mode. It can be considered that the ferromagnetic interaction between Ni2+ and Mn4+ gives rise to magnetic regions that pin the ferromagnetic LCMO and cause magnetic coupling at the LCMO/LNO interface.

Strain-Engineered Oxygen Vacancies in CaMnO3 Thin Films

“…Self-consistent Shirley-background subtraction and peak-fitting reveals that the Mn 3s splitting increases systematically with in-plane tensile strain (see Figure 3b). The low value of 4.49 eV is observed for the fully-relaxed bulk-like film (see Figure 3a), consistent with the prior studies and indicating predominantly Mn 4+ ion content [40][41][42] . The high value of 4.64 eV is observed for the maximallystrained (+4.0% tensile) film on the LSAT substrate (see Figure 3a), indicating a significant contribution of the lower-valent Mn 3+ ions, consistent with the XAS results.…”

Metal-insulator-metal transition in NdNiO3 films capped by CoFe2O4

“…Nickel possesses one electron in e g orbit in Ni 3+ state, as illustrated in Fig. 4(d This is similar to the scenario reported in the previous publication, 8,[28][29][30] and a further low-temperature XMCD (x-ray magnetic circular dichroism) is expected to give an insight into the respective contribution to magnetism during the transition. But this is not the case for the 3 u.c.…”

Charge Transfer and Orbital Reconstruction in Strain-Engineered (La,Sr)MnO3/LaNiO3 Heterostructures

“…The elongation of the outof-plane lattice parameters would stabilize the preferred 3z 2r 2 orbit occupancy. [34][35][36] Thus, it is concluded that the strain exerted by a comparatively thick LNO overlayer leads to orbital reconstruction.…”