Dependence of spin torque switching probability on electric current

TL;DR

This paper theoretically investigates how the probability of thermally assisted spin torque switching depends on electric current, deriving analytical expressions and highlighting the need for low-temperature experiments to determine key parameters.

Contribution

It provides analytical formulas for switching times with different current exponents, advancing understanding of spin torque switching mechanisms.

Findings

Switching current is proportional to temperature and logarithm of sweep rate.

Analytical expressions for switching times are derived for exponents b=1 and b=2.

Low-temperature experiments are necessary to determine the current exponent.

Abstract

Dependence of the thermally assisted spin torque switching probability on the sweep electric current was investigated theoretically. The analytical expressions of the switching times for $b=1$ and $b=2$ are derived based on the rate equation, where $b$ is the exponent of the current term in the switching rate. The switching current is approximately proportional to the temperature $T$ and the logarithm of the sweep rate $v$ for both $b=1$ and $b=2$ in the experimentally performed ranges of $T$ and $v$. Experiments in very low temperature range are required to determine the exponent $b$.