Magnetic coherent tunnel junctions with periodic grating barrier

Area of Science:

• Spintronics
• Condensed Matter Physics
• Materials Science

Background:

• Magnetic tunnel junctions (MTJs) are crucial for spintronic devices.
• Existing theories struggle to explain key phenomena in MgO-based MTJs, such as tunneling magnetoresistance (TMR) oscillations with barrier thickness and limitations in TMR values even with half-metallic electrodes.

Purpose of the Study:

• To develop a new spintronic theory for magnetic tunnel junctions (MTJs) with single-crystal barriers.
• To explain the oscillatory behavior of tunneling magnetoresistance (TMR) and its limitations.
• To propose pathways for enhancing TMR and enabling future MTJ designs.

Main Methods:

• Modeling the MTJ barrier as a diffraction grating with intralayer periodicity.
• Analyzing the coherence of diffracted electron waves in both charge and spin.
• Investigating the impact of barrier properties on TMR.

Main Results:

• The new theory successfully explains why TMR oscillates with barrier thickness in MgO-based MTJs.
• It addresses why TMR does not reach theoretical infinity even with half-metallic electrodes.
• The theory reproduces other principal features of TMR and suggests methods for modulation and enhancement.

Conclusions:

• The developed spintronic theory provides a novel framework for understanding MTJ behavior.
• It offers solutions for enhancing TMR and overcoming current limitations.
• A future-generation MTJ design is proposed, suitable for layered materials and industrial fabrication.