Vacuum diamagnetism of mesoscopic metallic samples

Zero-point energy of surface plasmon modes of mesoscopic metal samples in an external magnetic field has been considered. The magnetic response of plasmon vacuum has shown to be diamagnetic. In thin films this surface vacuum diamagnetism is at least of the same order of magnitude as the magnetism of the bulk electrons. Thus, a novel type of magnetism shown by thin metallic samples, which is complementary to the well known Pauli paramagnetic and Landau diamagnetic contributions to the magnetism of the electron gas has been demonstrated.