Medium dynamic field range linear bipolar spin valve sensor through soft pinning the sensing layer.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electrical Engineering

Background:

• Giant Magnetoresistance (GMR) spin valve sensors are crucial for applications like position and current sensing.
• Optimizing the magnetic properties and thermal stability of GMR sensors is essential for reliable performance.
• Controlling the bias field in spin valve structures is key to achieving desired sensor characteristics.

Purpose of the Study:

• To design and fabricate a magnetic sensor utilizing spin valve-GMR technology with a medium dynamic range.
• To enhance sensor performance through modification of the sensing layer (SL) with a soft pinning layer (SPL).
• To experimentally verify numerical simulations for controlling the bias field and assess the sensor's operational characteristics.

Main Methods:

• Modification of the spin valve stack by introducing a soft pinning layer (SPL) via an exchange bias field.
• Utilizing an antiferromagnetic layer with a lower blocking temperature adjacent to the pinned layer.
• Employing numerical simulations with a non-magnetic Ru spacer layer between the SPL and SL, followed by experimental verification.

Main Results:

• Fabrication of a magnetic sensor with a linear operating field range of approximately ±100 Oe.
• Achieved sensitivity of approximately 0.1 mV V^-1Oe^-1 near zero field.
• Demonstrated operational capability in the temperature range of -40°C to 125°C with a thermal coefficient of voltage around 15 µV V^-1°C^-1.

Conclusions:

• The modified spin valve-GMR sensor exhibits a medium dynamic range suitable for diverse applications.
• The implemented soft pinning layer strategy effectively controls the bias field and enhances sensor performance.
• The sensor demonstrates robust thermal performance, making it viable for a wide range of operating temperatures.