Photovoltaic effect in Au and Au-Fe microjunctions

Abstract

Recent work has shown that when a small conductor is exposed to a microwave electric field at low temperatures, a dc voltage is established. We have studied this photovolatic (PV) effect as a function of magnetic field, H, in Au microjunctions, some of which were doped with small concentrations (typically ∼50 ppm) of Fe. In the pure (undoped) samples the PV effect was independent of the sign of H, i.e., it was an even function of H. In contrast, the doped junctions displayed a PV signal which was an odd function of the magnetic field. This change in the symmetry of the PV effect appears to be associated with the localized magnetic moments of the Fe, but a theoretical explanation of this behavior is not currently available.