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Published on: July 5, 2019
Interlayer coupling in EuS/SrS, EuS/PbSe and EuS/PbTe magnetic semiconductor superlattices
H Kępa1, C F Majkrzak, A Sipatov
1Institute of Experimental Physics, 69 Hoża Street, 00-681 Warsaw, Poland. Physics Department, Oregon State University, 301 Weniger Hall, Corvallis, OR 97331, USA.
Summary
Neutron reflectivity studies revealed weak antiferromagnetic coupling in EuS/SrS and EuS/PbSe superlattices. No coupling was observed in EuS/PbTe, contrasting with theoretical predictions and prior findings for similar magnetic semiconductor superlattices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Magnetism
Background:
- Exchange interlayer coupling is crucial for understanding magnetic phenomena in superlattices.
- Europium sulfide (EuS) based magnetic semiconductor superlattices offer a platform to study these interactions.
- Previous studies on EuS/PbS showed significant antiferromagnetic coupling, providing a baseline for comparison.
Purpose of the Study:
- Investigate exchange interlayer coupling in EuS/SrS, EuS/PbSe, and EuS/PbTe all-semiconductor superlattices.
- Determine the influence of the nonmagnetic spacer material's electronic and structural properties on interlayer coupling.
- Compare experimental findings with theoretical predictions and existing data for EuS-based systems.
Main Methods:
- Neutron reflectivity studies were employed to probe the magnetic structure and coupling across interfaces.
- Superlattices with varying nonmagnetic spacer materials (SrS, PbSe, PbTe) were synthesized and characterized.
- Analysis focused on detecting and quantifying antiferromagnetic coupling between EuS layers.
Main Results:
- Weak antiferromagnetic coupling was observed in EuS/SrS and EuS/PbSe superlattices.
- No interlayer coupling was detected in EuS/PbTe superlattices.
- Observed coupling strengths were correlated with the energy gap of the spacer material and lattice mismatch.
Conclusions:
- The energy gap of the nonmagnetic spacer significantly influences interlayer coupling strength in EuS-based superlattices, as predicted for EuS/SrS.
- Findings for narrow-gap semiconductors EuS/PbSe and EuS/PbTe deviate from theoretical expectations and prior EuS/PbS results.
- Lattice mismatch may play a role in the observed magnetic ordering and lack of coupling in EuS/PbTe.
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