Spin Transfer Torque Random Access Memory

As semiconductor-based technologies such as SRAM and flash are predicted to reach their limitations in scaling, there has been a significant effort in developing the next generation of nonvolatile memory. One promising candidate to realize low-power operation and a high areal density nonvolatile memory is spin transfer torque random access memory (STT-RAM), which relies on the direction of magnetization for information storage and the transfer of angular momentum of spin polarized current for writing. In this chapter, the operation of STT-RAM is discussed. Experimental demonstrations that have allowed for the advancement of this technology are presented, including the development of perpendicular STT-RAM cells, methods to reduce the critical current density required for writing, and a design to achieve sub-200ps writing of STT-RAM cells. The current state-of-the-art demonstrations are presented along with perspectives on STT-RAM.