Control of Sub-Nanosecond Precessional Magnetic Switching in STT-MRAM Cells for SRAM Applications

STT-MRAM are foreseen as the best contender for DRAM replacement. STT-MRAM could also be used for SRAM applications if switching time below 1ns could be realized in a reliable way. In this study, we demonstrate that sub-ns switching with final state determined by the current polarity through the stack can be achieved in STT-MRAM cells comprising two spinpolarizing layers having orthogonal magnetic anisotropies [1],[2]. We carried out a thorough experimental and modeling study of these ultrafast STT-MRAM. We demonstrated that a quite reliable switching can be achieved by increasing the cell aspect ratio (AR) or advantageously by applying an in-plane static transverse field on the cell. Switching in 200ps could be demonstrated with write energy less than 100fJ.