  The interplay between Kondo screening, indirect magnetic interaction and
geometrical frustration is studied in the two-dimensional Kondo-necklace model
on the triangular lattice. Using infinite projected entangled pair states
(iPEPS), we compute the ground state as a function of the antiferromagnetic
local Kondo interaction $J_K$ and the Ising-type direct spin-spin interaction
$I_z$ . As opposed to previous studies, we do not find partial Kondo screening
(PKS) in the isotropic limit $I_z = 0$ but the same behavior as in the
unfrustrated case, i.e. a direct phase transition between the paradigmatic
phases of the Doniach competition: (i) a disordered phase consisting of local
spin-singlets at strong $J_K$ and (ii) a magnetically ordered phase at weak
$J_K$ . For $I_z > 0$, we find a PKS ground state but again in opposite to
previous studies, we find that the PKS ground state is in strong competition
with a second ground state candidate not found before. This state is
characterized by a strongly polarized central spin in each hexagon and its
anti-parallel, weakly polarized (i.e. partially screened) neighbors. We name it
central spin (CS) phase.
