  We conducted an infrared search for faint companions around 351 young stellar
objects in the rho Ophiucus molecular cloud and the Serpens molecular cloud.
Nine objects in the Spitzer/IRAC archival images were identified as young
stellar companion candidates. They showed an intrinsic infrared excess; one
object was extremely red both in the [3.6] - [4.5] color and in the [4.5] -
[5.8] color, and two objects were red in the [4.5] - [5.8] color. They were as
faint as 15 mag in the [3.6] band. Follow-up K-band spectroscopy revealed that
three objects had deep water absorption bands, indicative of low effective
temperatures. By comparing the spectra and infrared spectral energy
distributions with synthesized spectra of low-temperature objects, we derived
the effective temperatures and continuum excess for these objects. It seems
highly likely that one of the three objects is a low-mass stellar companion and
two objects are young brown dwarf companions associated with the young stellar
objects.
