  We present results of a high-resolution, near-infrared survey of 41 nearby,
young (<~300 Myr) M0-M5.0 dwarfs using the Altair natural guide star adaptive
optics system at the Gemini North telescope. Twelve of the objects appear to be
binaries, 7 of which are reported here for the first time. One triple system
was discovered. Statistical properties are studied and compared with earlier (F
to K) and later (>= M6 very low-mass, VLM) populations. We find that the
separation distribution of the binaries in this sample peaks at 13+14-9 AU,
which is consistent with previous measurements of early-M binaries. Hence,
early-M binaries seem to occur in--on average--tighter systems than G binaries.
At the same time they are significantly wider than field VLM binary stars. The
distribution of mass ratios q of primary and secondary stars was found to show
an intermediate distribution between the strongly q-->1 peaked distribution of
field VLM systems and the almost flat distribution of earlier-type stars.
Consequently, we show evidence for relatively young, early-M binaries
representing a transition between the well known earlier star distributions and
the recently examined field VLM population characteristics. Despite the fact
that this survey was dedicated to the search for faint brown dwarf and
planetary mass companions, all planetary mass candidates were background
objects. We exclude the existence of physical companions with masses greater
than 10 Jupiter masses (M_Jup) at separations of >~40 AU and masses greater
than 24 M_Jup for separations >~10 AU around 37 of the 41 observed objects.
