Low hysteresis FeMn-based top spin valve

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spintronics

Background:

• FeMn-based materials are key components in spintronic devices like spin valves.
• Controlling magnetization reversal and maximizing the giant magnetoresistance (GMR) effect are critical for device performance.
• Low-field hysteresis can impede the sensitivity and operational range of magnetic sensors.

Purpose of the Study:

• To investigate the impact of copper (Cu) and iron-manganese (FeMn) layer thicknesses on spin valve properties.
• To minimize low-field hysteresis in Ta/[FeNi/CoFe]/Cu/CoFe/FeMn/Ta spin valves.
• To maintain a high GMR ratio while reducing hysteresis.

Main Methods:

• Fabrication of spin valves using DC magnetron sputtering at room temperature.
• Systematic variation of Cu and FeMn layer thicknesses.
• Characterization of magnetic properties including GMR ratio and hysteresis loops.
• Utilizing non-collinear geometry in magnetoresistance measurements.

Main Results:

• Achieved significant reduction in low-field hysteresis, down to 0.1-0.2 Oe.
• Maintained a GMR ratio exceeding 8% through optimization.
• Demonstrated dependence of hysteresis and GMR on the angle between the applied magnetic field and pinning direction.

Conclusions:

• Optimized layer thicknesses and non-collinear measurement geometry are effective in reducing low-field hysteresis in FeMn-based spin valves.
• The study provides a pathway for developing highly sensitive magnetic sensors with improved performance.
• Understanding the angular dependence is crucial for fine-tuning spin valve characteristics.