  Recent (sub)millimeter polarimetric observations toward the young star HL Tau
have successfully detected polarization emission from its circumstellar disk.
The polarization pattern observed at 0.87 mm is uniform and parallel to the
disk's minor axis, consistent with the self-scattering of thermal emission by
dust particles whose maximum radius is $\approx 100~\mu m$. However, this
maximum size is considerably smaller than anticipated from dust evolution
models that assume a high sticking efficiency for icy particles. Here, we
propose that the unexpectedly small particle size can be explained if CO$_2$
ice covers the particles in the outer region of the HL Tau disk. CO$_2$ ice is
one of the most major interstellar ices, and laboratory experiments show that
it is poorly sticky. Based on dust evolution models accounting for CO$_2$ ice
mantles as well as aggregate sintering and post-processing radiative transfer,
we simulate the polarimetric observation of HL Tau at 0.87 mm. We find that the
models with CO$_2$ ice mantles better match the observation. These models also
predict that only particles lying between the H$_2$O and CO$_2$ snow lines can
grow to millimeter to centimeter sizes, and that their rapid inward drift
results in a local dust gap similar to the 10 au gap of the HL Tau disk. We
also suggest that the millimeter spectral index for the outer part of the HL
Tau disk is largely controlled by the optical thickness of this region and does
not necessarily indicate dust growth to millimeter sizes.
