Tunnel barriers for Fe-based spin valves providing high spin-polarized current

Area of Science:

• Materials Science
• Condensed Matter Physics
• Quantum Mechanics

Background:

• Magnetic tunnel junctions (MTJs) are crucial for spintronic devices.
• Developing efficient tunnel barrier materials is key to improving MTJ performance.

Purpose of the Study:

• To investigate the suitability of CdS, ZnS, Cd3ZnS4, and Zn3CdS4 as tunnel barriers in MTJs.
• To evaluate their potential for enhancing spin-polarized current and tunneling magnetoresistance.

Main Methods:

• Ground state quantum mechanical calculations using density functional theory (DFT).
• Transport calculations employing the non-equilibrium Green's function (NEGF) method.

Main Results:

• The valence and conduction band edges of the investigated semiconductors are dominated by specific orbital symmetries (p and s, respectively).
• Fe/semiconductor/Fe MTJs exhibit significant Δ1 symmetry filtering of Bloch states.
• Achieved tunneling magnetoresistance and spin-polarized current are substantially higher than in Fe/MgO/Fe MTJs.

Conclusions:

• CdS, ZnS, Cd3ZnS4, and Zn3CdS4 show promise as high-performance tunnel barriers.
• The observed electronic structure facilitates efficient spin filtering, leading to enhanced spintronic properties.