Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Validity of the thermal activation model for spin-transfer torque switching in magnetic tunnel junctions



Ranko R. Heindl, William H. Rippard, Stephen E. Russek, Matthew R. Pufall, Anthony B. Kos


We have performed spin transfer switching experiments on nanoscale MgO magnetic tunnel junctions, with a large number of trials (up to 107 switching events) as functions of pulse voltage amplitude and duration, and compared the results with both macrospin simulations and a simple thermal model of switching. Three different methods derived from the thermally activated spin-torque-assisted switching model are used to determine the thermal stability factor and the intrinsic switching voltage from the switching distributions. Specifically, their values are determined from the read disturb rate, switching voltage vs. pulse duration, and switching voltage distribution measurements. Our conclusion is that the data obtained from the first two methods agree well with each other as well as with the values from quasistatic measurements, assuming that for the region of voltages over which the data is taken, the voltage is small compared to the intrinsic switching voltage, and the influence from other factors contributing to the switching is negligible (such as current-induced heating and field-like torque). The third method (switching voltage distribution measurements) is shown to be impractical, because the applied voltage surpasses the intrinsic switching voltage within the time-scale (
Physical Review B


MRAM, STT-RAM, spin-transfer switching, current-induced switching, thermal stability, nonvolatile memory


Heindl, R. , Rippard, W. , Russek, S. , Pufall, M. and Kos, A. (2011), Validity of the thermal activation model for spin-transfer torque switching in magnetic tunnel junctions, Physical Review B, [online], (Accessed May 26, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created April 6, 2011, Updated November 10, 2018