Probing the response of metals to low-frequency s-polarized evanescent fields

¹ Central Astronomical Observatory at Pulkovo of the Russian Academy of Sciences - Saint Petersburg, 196140, Russia
² Peter the Great Saint Petersburg Polytechnic University - Saint Petersburg, 195251, Russia
³ Kazan Federal University - Kazan, 420008, Russia
⁴ Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences Leninsky prospect 31 bld. 4, 119071 Moscow, Russia

^(a) g.klimchitskaya@gmail.com (corresponding author)

Received: 11 July 2022
Accepted: 24 August 2022

Abstract

An experimental test for the response function of metals to the low-frequency s-polarized evanescent waves is proposed by measuring the lateral component of the magnetic field of an oscillating magnetic dipole spaced above a thick metallic plate. This suggestion is motivated by the fact that the Lifshitz theory using the Drude response function is in contradiction with high-precision measurements of the Casimir force performed at separations exceeding 150 nm. Analytic expressions for the lateral components of the magnetic field, which are fully determined by the s-polarized evanescent waves, are reported in terms of the reflection coefficients of the plate metal. Numerical computations are performed for the reasonable values of the experimental parameters for different models of the dielectric response. The resulting fields differ by the orders of magnitude depending on whether the Drude or plasma response function is used in computations. Thus, the measurement of the magnetic field will allow to discriminate between these two options. Possible applications of the obtained results are discussed.