We studied the spin transfer torque (STT) driven switching voltage distribution systematically by characterizing the switching probability density function (PDF) with large statistics (10 5 trials) across a wide time scale from 5 ns to 1 μs. The skew normal distribution function is found to be a good one to fit the measured switching PDF down to low values, which would be used as a guideline to extrapolate read disturb rate (RDR) and write error rate (WER) in STT-RAM design. Moreover, the asymmetry of switching probability density function is observed to flip when the pulse width decreases. It is related to the fluctuation mechanism transition from the thermal agitation to the initial magnetization trajectory dispersion.
Bibliographical noteFunding Information:
This work was supported in part by the DARPA STT-RAM program (Grant No. HR0011-09-C-0114) and NSF MRSEC Program at University of Minnesota (Grants No. DMR-0819885). The work of J.-P. Wang, H. Zhao, and Y. Zhang was supported in part by an Intel University Research Grant.
- Magnetic tunnel junction
- spin transfer torque switching