  We study the impact of nonhermiticity due to strong correlations in
f-electron materials. One of the most remarkable phenomena occurring in
nonhermitian systems is the emergence of exceptional points at which the
effective nonhermitian Hamiltonian becomes non-diagonalizable. We here
demonstrate that Kondo temperature is related to the temperature at which
exceptional points appear around the Fermi level. For this purpose, we study
the periodic Anderson model with local and nonlocal hybridization in the
insulating and metallic regimes. By analyzing the effective nonhermitian
Hamiltonian, which describes the single-particle spectral function, and the
temperature dependence of the screening of the magnetic moment, from which the
Kondo temperature can be found, we show that exceptional points appear at the
temperature at which the magnetic moment is screened. These results suggest
that the well-known crossover between localized and itinerant f electrons in
$f$-electron materials is related to the emergent exceptional points in the
single-particle spectral function.
