研究目的
Investigating the spin splitting in ferromagnetic EuO grown on Si(111) substrates and its implications for spin-filter tunnel junctions.
研究成果
The study successfully demonstrated spin splitting in EuO(111)/Si(111) spin-filter tunnel junctions with atomically sharp interfaces, achieving a spin polarization above 90%. The optimal Eu-termination for high crystalline quality was identified, and the spin splitting energy was quantified. Future work should explore the electron affinity and J-V characteristics under magnetic fields.
研究不足
The study is limited by the Curie temperature of the EuO films, which was lower than that of bulk EuO, potentially due to oxygen-rich layers. The thickness of the EuO films also limited the measurement range for tunnel resistance.
1：Experimental Design and Method Selection:
The study involved the epitaxial growth of EuO on Si(111) substrates using molecular beam epitaxy (MBE) to achieve high crystal quality and atomically sharp interfaces. The spin splitting and barrier height lowering below the Curie temperature were investigated.
2：Sample Selection and Data Sources:
Si(111) substrates were prepared with a wet chemical process, and EuO films were grown with various Eu-terminations to optimize crystalline quality.
3：List of Experimental Equipment and Materials:
MBE system, X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), reflection high-energy electron diffraction (RHEED), and a source measure unit (Keithley 2635B) for J-V measurements.
4：Experimental Procedures and Operational Workflow:
EuO films were grown on Si(111) substrates with different Eu-terminations, characterized by XRD and STEM, and tunnel junction devices were fabricated to measure the temperature dependence of the tunnel current.
5：Data Analysis Methods:
The spin splitting energy and spin polarization were determined from the temperature dependence of the tunnel current using the Simmons model.
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