Temperature dependence of the non-Hermitian skin effect associated with Kondo crossover

Strongly correlated systems (SCS) have many exciting phenomena, such as the Kondo effect. In the Kondo effect, the interaction between conduction electrons and localized impurities causes a characteristic change in physical quantities around the Kondo temperature.

Furthermore, non-hermitian (NH) systems have attracted much attention. The eigenvalues are complex due to the breaking of the hermiticity, and a wide range of novel phenomena are observed. The non-hermitian skin effect (NHSE) is a topological phenomenon unique to NH systems, where the eigenstates are localized near the boundaries.

Recently, the equivalence between SCS and NH systems has been pointed out. In particular, the Kondo temperature is related to the appearance of exceptional points in the effective NH Hamiltonian [1].

In this study, we numerically investigate the impact of the Kondo effect on the NHSE using an f-electron system described by the periodic Anderson model. The spin-orbit interaction induces the NHSE, protected by the time-reversal symmetry. We also show that the behavior of localized modes changes near the Kondo temperature in terms of generalized Brillouin zones [2] and pseudo-spectra [3].

[1] Y. Michishita, R. Peters, Phys. Rev. Lett. 124, 196401 (2020)

[2] K. Yokomizo and S. Murakami, Phys. Rev. Lett. 123, 066404 (2019)

[3] N. Okuma and M. Sato, Phys. Rev. Lett. 126, 176601 (2021)