  Hadron spectroscopy provides direct physical measurements that shed light on
the non-perturbative behavior of quantum chromodynamics (QCD). In particular,
various exotic hadrons such as the newly observed $T_{cc}^+$ by the LHCb
collaboration, offer unique insights on the QCD dynamics in hadron structures.
In this letter, we demonstrate how heavy ion collisions can serve as a powerful
venue for hadron spectroscopy study of doubly charmed exotic hadrons by virtue
of the extremely charm-rich environment created in such collisions. The yields
of $T_{cc}^+$ as well as its potential isospin partners are computed within the
molecular picture for Pb-Pb collisions at center-of-mass energy
$2.76~\mathrm{TeV}$. We find about three-order-of-magnitude enhancement in the
production of $T_{cc}^+$ in Pb-Pb collisions as compared with the yield in
proton-proton collisions, with a moderately smaller enhancement in the yields
of the isospin partners $T_{cc}^0$ and $T_{cc}^{++}$. The $T_{cc}^+$ yield is
comparable to that of the $X(3872)$ in the most central collisions while shows
a considerably stronger decrease toward peripheral collisions, due to a
"threshold" effect of the required double charm quarks for $T_{cc}^+$. Final
results for their rapidity and transverse momentum $p_T$ dependence as well as
the elliptic flow coefficient are reported and can be tested by future
experimental measurements.
