  The magnetic, transport, and structural properties of (Ga,Cr)As are reported.
Zincblende Ga$_{1-x}$Cr$_{x}$As was grown by low-temperature molecular beam
epitaxy (MBE). At low concentrations, x$\sim$0.1, the materials exhibit unusual
magnetic properties associated with the random magnetism of the alloy. At low
temperatures the magnetization M(B) increases rapidly with increasing field due
to the alignment of ferromagnetic units (polarons or clusters) having large
dipole moments of order 10-10$^2$$\mu_B$. A standard model of
superparamagnetism is inadequate for describing both the field and temperature
dependence of the magnetization M(B,T). In order to explain M(B) at low
temperatures we employ a distributed magnetic moment (DMM) model in which
polarons or clusters of ions have a distribution of moments. It is also found
that the magnetic susceptibility increases for decreasing temperature but
saturates below T=4 K. The inverse susceptibility follows a linear-T
Curie-Weiss law and extrapolates to a magnetic transition temperature
$\theta$=10 K. In magnetotransport measurements, a room temperature resistivity
of $\rho$=0.1 $\Omega$cm and a hole concentration of $\sim10^{20}$ cm$^{-3}$
are found, indicating that Cr can also act as a acceptor similar to Mn. The
resistivity increases rapidly for decreasing temperature below room
temperature, and becomes strongly insulating at low temperatures. The
conductivity follows exp[-(T$_1$/T)$^{1/2}$] over a large range of
conductivity, possible evidence of tunneling between polarons or clusters.
