  Motivated by recent experiments on $^{6}$Li-$^{133}$Cs atomic mixtures with
high mass imbalance, we study the Efimov correlation in atomic system of two
heavy bosons ($^{133}$Cs) immersed in a bath of light fermions ($^{6}$Li).
Using the Born-Oppenheimer approximation, we identify two different regimes,
depending on the Fermi momentum of light fermions ($k_F$) and the boson-fermion
scattering length $a_s(<0)$, where the presence of underlying Fermi sea plays
distinct roles in the Efimov-type binding of bosons. Namely, in the regime
$k_F|a_s|\lesssim 1$ ($k_F|a_s|\gtrsim1$), the Fermi sea induces an attractive
(repulsive) effective interaction between bosons and thus favors (disfavors)
the formation of bound state, which can be seen as the Efimov trimer dressed by
the fermion cloud. Interestingly, this implies a non-monotonic behavior of
these bound states as increasing the fermion density (or $k_F$). Moreover, we
establish a generalized universal scaling law for the emergence/variation of
such dressed Efimov bound states when incorporating a new scale ($k_F$) brought
by the Fermi sea. These results can be directly tested in Li-Cs cold atoms
experiment by measuring the modified bound state spectrum and the shifted
Efimov resonance, which manifest an emergent non-trivial Efimov correlation in
a fermionic many-body environment.
