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Spin-polarized inelastic tunneling through insulating barriers.
1Unité Mixte de Physique CNRS/Thales, Campus Polytechnique, 1 Avenue Augustin Fresnel, 91767 Palaiseau Cedex and Université Paris-Sud 11, 91405, Orsay, France.
Physical Review Letters
|June 13, 2009
Summary
Spin-conserving transport in magnetic tunnel junctions reveals inelastic tunneling through localized states. Boron-doped MgO barriers activate these channels, reducing magnetoresistance effects.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Transport
Background:
- Magnetic tunnel junctions (MTJs) with CoFeB-MgO-CoFeB structures exhibit high spin polarization.
- Understanding transport mechanisms in MTJs is crucial for spintronic device development.
Purpose of the Study:
- To investigate spin-conserving hopping transport through localized states in MTJs.
- To analyze the role of boron-doped MgO barriers in activating inelastic tunneling channels.
- To extend existing theories for inelastic tunneling to ferromagnetic systems.
Main Methods:
- Experimental fabrication and characterization of CoFeB-MgO-CoFeB magnetic tunnel junctions.
- Electrical transport measurements to probe spin-polarized tunneling phenomena.
- Theoretical modeling based on an extension of the Glazman-Matveev theory.
Main Results:
- Evidence of spin-conserving hopping transport through chains of localized states was observed.
- Relatively thick, boron-doped MgO barriers were found to favor spin-conserving inelastic channels.
- These activated channels led to a reduction in magnetoresistance effects.
Conclusions:
- Spin-polarized inelastic tunneling through localized states in insulating barriers is feasible.
- Boron doping in MgO barriers can tune transport properties by activating specific inelastic channels.
- The extended Glazman-Matveev theory provides a framework for understanding spin-polarized inelastic tunneling in MTJs with ferromagnetic reservoirs.
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