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Static Magnetic Proximity Effect in Pt/NiFe2O4 and Pt/Fe Bilayers Investigated by X-Ray Resonant Magnetic
T Kuschel1, C Klewe1, J-M Schmalhorst1
1Center for Spinelectronic Materials and Devices, Department of Physics, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany.
Physical Review Letters
|September 16, 2015
Summary
Spin polarization in platinum (Pt) layers on magnetic materials was investigated. The study found significant spin polarization in Pt/Fe but negligible polarization in Pt/NiFe2O4, clarifying effects in spintronic devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Understanding interfacial magnetism is crucial for spintronic devices.
- Magnetic proximity effects influence material properties at interfaces.
- Distinguishing between different magnetic interactions is key for device optimization.
Purpose of the Study:
- To quantify spin polarization in platinum (Pt) layers adjacent to NiFe2O4 and Fe.
- To investigate static magnetic proximity effects at these interfaces.
- To clarify the influence of proximity effects on thermoelectric phenomena.
Main Methods:
- Interface-sensitive x-ray resonant magnetic reflectivity (XRR) was employed.
- Measurements were conducted at the Pt L3 absorption edge using circularly polarized X-rays.
- Ab initio calculations were used for theoretical comparison.
Main Results:
- A significant asymmetry ratio of 2% was observed for Pt/Fe bilayers, independent of Pt thickness (1.8-20 nm).
- The maximum induced magnetic moment in Pt/Fe was determined to be (0.6±0.1) μB per spin-polarized Pt atom.
- For Pt/NiFe2O4, the asymmetry ratio was below 0.02 μB per Pt atom, indicating negligible spin polarization.
Conclusions:
- The study confirms substantial spin polarization in Pt/Fe due to proximity effects.
- Negligible spin polarization in Pt/NiFe2O4 suggests the longitudinal spin Seebeck effect is not influenced by proximity-induced anomalous Nernst effect.
- These findings help differentiate magnetic contributions in layered spintronic materials.
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