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Spin transfer in magnetic tunnel junctions with hot electrons
1Thales Research Center, Unité Mixte de Physique CNRS-THALES, Route Départementale 128, 91767 Palaiseau, France.
Physical Review Letters
|October 10, 2006
Summary
Spin transfer torque in magnetic tunnel junctions remains effective even when magnetoresistance decreases. Hot electrons enhance charge current and spin transfer, maintaining torque efficiency across varying bias voltages.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Spintronics
Background:
- Magnetic tunnel junctions (MTJs) are crucial for spintronic devices.
- Spin transfer torque (STT) is a key phenomenon in MTJs, enabling magnetic switching.
- Bias dependence of STT and its interplay with magnetoresistance (MR) are critical for device performance.
Purpose of the Study:
- To investigate the bias dependence of spin transfer torque in magnetic tunnel junctions.
- To understand the role of hot electrons in modulating STT and magnetoresistance.
- To determine if the ratio of torque to charge current is affected by reduced magnetoresistance.
Main Methods:
- Analysis of experimental data on bias dependence in MTJs.
- Theoretical modeling of current-induced excitations (hot electrons).
- Quantification of charge current, spin transfer, and torque at varying bias voltages.
Main Results:
- Spin transfer torque remains largely intact at bias voltages where tunneling magnetoresistance is significantly reduced.
- Current-induced hot electron excitations reduce magnetoresistance but enhance both charge current and spin transfer.
- The ratio of spin transfer torque to charge current shows minimal change despite reduced magnetoresistance.
Conclusions:
- Hot electrons play a significant role in the bias-dependent behavior of MTJs.
- MTJs can maintain efficient spin transfer torque operation even under conditions of reduced magnetoresistance.
- These findings have implications for the design and optimization of spintronic devices.
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