  The exotic electronic states in the charge loop current (cLC) phase, in which
the permanent charge current breaks the time-reversal-symmetry (TRS), have been
attracting increasing attention in recently discovered kagome metal AV3Sb5 (A =
Cs, Rb, K). Interestingly, the cLC state is sensitively controlled by applying
small magnetic field as well as tiny uniaxial strain. In addition, many
experiments indicate that the cLC state is extremely sensitive to the small
number of impurities. To understand the impurity effects on the cLC electronic
states accurately, we analyze the giant unit-cell (up to 300 sites) kagome
lattice model with single impurity potential. The loop current is found to be
strongly suppressed within the current correlation length $\xi_J$ centered on
the impurity site, where $\xi_J$ is inversely proportional to the cLC order
parameter $\eta$. (The cLC order is the pure imaginary hopping integral
modulation $\delta t_{i,j}=\pm i\eta$.) In addition, both the uniform orbital
magnetization $M_{orb}$ and the anomalous Hall conductivity $\sigma_{xy}$ are
drastically suppressed by dilute impurities. Especially, the suppression ratio
$R=-\Delta M_{orb}/M_{orb}^0$ can exceed 50% by introducing $\sim1\,\%$
impurities. Unexpectedly, the ratio $R$ is insensitive to $\eta$, in highly
contrast to a naive expectation that $R$ is proportional to the current
suppression area $\pi \xi_J^2$. The obtained giant impurity effect of $M_{orb}$
would originate from the non-local contribution from the itinerant circulation
of electrons. The present study gives a natural explanation why the cLC
electronic states in kagome metals are extremely sensitive to the dilute
impurities.
