  We present results of a study of intermittency and multifractality of
magnetic structures in solar active regions (ARs). Line-of-sight magnetograms
for 214 ARs of different flare productivity observed at the center of the solar
disk from January 1997 until December 2006 are utilized. Data from the
Michelson Doppler Imager (MDI) instrument on-board the {\it Solar and
Heliospheric Observatory} (SOHO) operating in the high resolution mode, the Big
Bear Solar Observatory digital magnetograph and {\it Hinode} SOT/SP instrument
were used. Intermittency spectra were derived via high-order structure
functions and flatness functions. The flatness function exponent is a measure
of the degree of intermittency. We found that the flatness function exponent at
scales below approximately 10 Mm is correlated to the flare productivity (the
correlation coefficient is - 0.63). {\it Hinode} data show that the
intermittency regime is extended toward the small scales (below 2 Mm) as
compared to the MDI data. The spectra of multifractality, derived from the
structure functions and flatness functions, are found to be more broad for ARs
of highest flare productivity as compared to that of low flare productivity.
The magnetic structure of high-flaring ARs consists of a voluminous set of
monofractals, and this set is much richer than that for low-flaring ARs. The
results indicate relevance of the multifractal organization of the photospheric
magnetic fields to the flaring activity. Strong intermittency observed in
complex and high-flaring ARs is a hint that we observe a photospheric imprint
of enhanced sub-photospheric dynamics.
