  We propose a method for calculating the isothermal critical exponent $\delta$
in Ising systems undergoing a second-order phase transition. It is based on the
calculation of the mean magnetization time series within a small connected
domain of a lattice after equilibrium is reached. At the pseudocritical point,
the magnetization time series attains intermittent characteristics and the
probability density for consecutive values of mean magnetization within a
region around zero becomes a power law. Typically the size of this region is of
the order of the standard deviation of the magnetization. The emerging
power-law exponent is directly related to the isothermal critical exponent
$\delta$ through a simple analytical expression. We employ this method to
calculate with remarkable accuracy the exponent $\delta$ for the square-lattice
Ising model where traditional approaches, like the constrained effective
potential, typically fail to provide accurate results.
