Suppressed magnetic ordering at the surface of layered manganites.

The double layered manganite La2-2xSr1+2xMn2O7 is a high spin-polarization material with a metallic-ferromagnetic phase near x=0.36. Understanding the magnetic surface properties is key as they affect spin-transport in hybrids structures that use this class of materials. Soft x-ray resonant magnetic scattering (XRMS) at the Mn L3 edge was used to obtain the magnetization density profile in the near-surface region. The energy dependence of this scattering at q=16° shows that the magnetization in the surface bilayer (1 nm thick) is strongly suppressed while the layers underneath retain full magnetization. Since the thin non-magnetic bilayer is also an insulator, it can serve as an intrinsic barrier in magnetic tunnel junction devices [Nature Materials 4, 62 (2005)].

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