Suppression of the Low-Temperature Increase in the Van Der Waals Force by the Anomalous Skin Effect

A giant (by six to eight orders of magnitude) increase in the van der Waals force between pure metal plates when the temperature drops from 100 to 1 K A was predicted in [G. V. Dedkov, JETP Lett. 114, 779 (2021)]. The calculation is based on the local Drude model, the applicability of which is limited by the condition l $$ \ll $$ d, where l is the mean free path of electrons and d is the distance between the bodies. In ultrapure metals at low temperatures, the anomalous skin effect (l $$ \gg $$ d) occurs and the local model loses its physical validity. It has been shown the nonlocal response strongly suppresses the contribution of S-polarized evanescent modes. As a result, the predicted increase in the force is absent at l $$ \gg $$ d. The limits of the applicability of the local and nonlocal approaches are established, which is important for the correct description of fluctuation friction in pure metals.