  The effect of non-uniform magnetic fields on the Ising-Heisenberg chain of a
heterotrimetallic coordination compound $\mathrm{Fe-Mn-Cu}$, modeling a
magnetic impurity on one dimer is studied. This impurity is configured by
imposing non-uniform magnetic fields on each sites of $j-$th interstitial ionic
dimer $\mathrm{Mn}^{2+}-\mathrm{Cu}^{2+}$ of the chain model. The quantum
coherence and pairwise entanglement between spin-1/2 magnetic
$\mathrm{Mn}^{2+}-\mathrm{Cu}^{2+}$ ion dimers clearly depend on the site which
the impurity is located. It is demonstrated that when the magnetic impurity is
considered for one magnetic dimer, by altering Ising nodal exchange interaction
and Heisenberg anisotropy parameter of the impurity dimer, the entanglement can
be enhanced to the maximal value 1 at a special fixed magnetic field. Moreover,
we find that the quantum Fisher information of the model with magnetic impurity
behaves considerably different from the original model. Besides of the quantum
resources like concurrence, we prove that the quantum Fisher information can be
used as new quantum tool for estimating the quantum phase transition in the
model under consideration. On the other hand, thermal teleportation can be
significantly optimized by adjusting the magnetic impurity, and a strong
increase in the average fidelity is observed. Finally, the magnetic impurity
can be manipulated to locally control the thermal entanglement, coherence,
quantum Fisher information and teleportation unlike the original model where it
is done globally.
