Spin-Transfer-Torque MRAM: The Next Revolution in Memory

Spin-Transfer-Torque MRAM was invented at IBM by John Slonczewski in the early 1990s. By using a spin-polarized current, instead of a magnetic field, to write a magnetic free layer in a magnetic tunnel junction, the required write current naturally decreases with area, providing attractive technology scaling. The discovery of high magnetoresistance in MgO tunnel barriers at IBM by Stuart Parkin, and later independently by Shinji Yuasa, enabled sufficient read signal to efficiently read magnetic tunnel junctions. The discovery of perpendicular magnetic anisotropy in thin CoFeB/MgO layers at IBM and independently by Tohoku University enabled a dramatic reduction in the switching current, and opened the way to practical perpendicular magnetic tunnel junctions for dense Spin-Transfer-Torque MRAM.
This talk will provide an overview of Spin-Transfer-Torque MRAM, including the three basic building blocks described above. I’ll give an introduction to the basic physics of spin-transfer torque and applications of Spin-Transfer-Torque MRAM. Then I will review why perpendicular magnetic anisotropy is advantageous for MRAM compared to in-plane anisotropy, and the materials challenges of perpendicular anisotropy. I will discuss the research at IBM in 2009 that led to our discovery of perpendicular anisotropy in thin CoFeB/MgO layers, and our use of these layers to make the first practical perpendicular magnetic tunnel junctions and the first demonstration of reliable writing in Spin-Transfer-Torque MRAM. Finally I will review our recent results on methods to lower the switching current of Spin-Transfer-Torque MRAM by using optimized magnetic materials and double magnetic tunnel junctions, including our recent demonstration of reliable 250 ps switching.
Speaker(s): Dr. Worledge,
Bldg: Quadrant, 1120 Ringwood Ct., San Jose, California, United States, 95131, Virtual: https://events.vtools.ieee.org/m/371928