  Most stars form in multiple systems whose properties can significantly impact
circumstellar disk evolution. We investigate the physical and chemical
properties of the equal-mass, small separation (~66 mas, ~9 au) DF Tau binary
system. Previous observations indicated that only DF Tau A has a circumstellar
disk. We present JWST-MIRI MRS observations of DF Tau. The MIRI spectrum shows
a forest of H2O lines and emission from CO, C2H2, HCN, CO2, and OH. LTE slab
models are used to determine the properties of the gas, and we analyze high
angular spatial and spectral resolution data from ALMA, VLTI-GRAVITY, and
IRTF-iSHELL to aid in the interpretation of the JWST data. The 1.3 mm ALMA
continuum data show two equal-brightness sources of compact (R<3 au) emission,
with separations and movement consistent with astrometry from VLTI-GRAVITY and
the known orbit. This is interpreted as a robust detection of a disk around DF
Tau B, which we suggest may host a small (~1 au) cavity to reconcile all
observations. The disk around DF Tau A is expected to be a full disk, and
spatially and spectrally resolved dust and gas emission points to hot, close-in
(<0.2 au) material. Hot (~500-1000 K) H2O, HCN, and C2H2 emission in the MIRI
data likely originate in the DF Tau A disk, while a cold (<200 K) H2O component
with an extended emitting area is consistent with an origin from both disks.
Despite the very compact outer disks, the inner disk composition and conditions
are similar to isolated systems, suggesting that the close binary nature is not
a driving factor in setting the inner disk chemistry. However, constraining the
geometry of the disks, for instance, via higher resolution ALMA observations,
would provide additional insight into the mid-infrared gas emission. JWST
observations of spatially resolved binaries will be important for understanding
the impact of binarity on inner disk chemistry more generally.
