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A novel nonvolatile static random access memory cell is proposed that consists of four transistors and two spin-transfer-torque magnetic tunnel junctions (STT-MTJs). In the case of the NFET driver cell, the free layers of the magnetic tunnel junctions are connected to the transistors' sources and drains to make the cell read-disturb free. The static power is totally eliminated as the power line is shut down during data hold. The static noise margin of the cell is calculated based on the experimental data on MTJ switching that is enhanced from the resistive load SRAM cell due to the MTJ's switching operation. The cell size is estimated to become smaller than the 6-transistor SRAM cell when it is designed at 45 nm node and beyond owing to the MTJ's area shrink as well as the thinning of its tunnel dielectrics (MgO).

The time-resolved switching characteristics of 100×200 nm2 size CoFeB/MgO/CoFeB-based magnetic tunnel junction (MTJ) are investigated by using the 20 GHz sampling measurement technique. We focused on the physical quantities of the time-resolved characteristics such as incubation time t A, transit time t B, and the standard deviations σV's of the period of the switching waveform. Furthermore, the dependencies of t A and t B on the applied pulse waveforms are analyzed. We found t A exponentially decreases as the applied voltage to MTJ increases, while t B remains less than two nano seconds regardless of the applied voltage. Furthermore, it is observed that the standard deviations of the waveform during t A is larger than that of the other periods. Finally, we discuss the switching characteristics with proposed toy model based on spin transfer torque (STT) phenomena.