Field-Free Spin-Orbit Torque Switching in Wedge-Shaped Pt/Co/Ta for High-Performance Neuromorphic Devices

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spintronics

Background:

• Perpendicularly magnetized heterostructures offer high-density, low-power nonvolatile memory via spin-orbit torque.
• Current methods require an in-plane magnetic field, hindering device integration.

Purpose of the Study:

• Investigate field-free spin-orbit torque switching in obliquely sputtered Pt/Co/Ta heterostructures.
• Enable multilevel information storage and artificial neural network applications.

Main Methods:

• Utilized oblique sputtering to control magnetic moment tilt in Pt/Co/Ta heterostructures.
• Adjusted current pulse width and amplitude to achieve multiple resistance states.
• Optimized magnetization switching curves for compatibility with rectified linear unit activation functions.

Main Results:

• Demonstrated field-free spin-orbit torque switching enabled by oblique deposition.
• Successfully mimicked synaptic behaviors (LTP/LTD, EPSP/IPSP) using multiple resistance states.
• Achieved 93.38% classification accuracy on CIFAR-10 using a convolutional neural network with these devices.

Conclusions:

• Oblique sputtering is a viable method for field-free spin-orbit torque switching.
• These devices show significant potential for advanced machine learning and neuromorphic computing.
• The technology is practical for real-world applications in artificial intelligence.