Dan Ralph


Photo of Dan Ralph

Challenges and Opportunities in Spintronics

The utilization of the electron’s spin as well as its charge, achieved by integrating magnetic materials and devices within CMOS architectures, can enable capabilities not easily achievable using charge-based semiconductors alone.  Magnetic devices permit non-volatile memories in which switching occurs via reorientation of a magnetic moment, with no motion of atoms.  This allows low-voltage operation with near-infinite endurance, a combination that is difficult to achieve using competing technologies based on atomic rearrangements or charge motion at larger voltages.  A first generation of spin-transfer-torque magnetic random access memory is being successfully commercialized, and recent advances in physics and materials science suggest strategies for substantial further improvements in energy efficiency, speed, and density.  I will describe some of the recent progress in this field, and highlight opportunities by which research into interface engineering, new materials, and utilization of topological electron bandstructures might accelerate future spintronics technologies.


Dan Ralph is the F. R. Newman Professor of Physics at Cornell University. His research encompasses the electronic, magnetic, and optical properties of nanoscale materials and devices. At present, the main focus of his research group is “spintronics” – how new functionality can be achieved in electronic devices by taking advantage of the electron’s spin as well as charge. Together with his Cornell colleague Bob Buhrman, Dr. Ralph’s group was the first to demonstrate switching of magnetic devices using the spin-transfer torque effect, an advance which sparked the commercial development of a new form of non-volatile magnetic random access memory, STT-MRAM. His research group is currently working to understand even more efficient forms of magnetic manipulation. Dr. Ralph is a graduate of Cornell’s Physics Ph.D. program. He is a former Director of the Cornell Nanofabrication Facility and also Cornell’s Laboratory of Atomic and Solid State Physics. He is a recipient of the William L. McMillan Award in Condensed Matter Physics, Packard and Sloan Foundation Fellowships, and the Merrill Teaching Award at Cornell.