Search for electrical current resonance and current echoes

Abstract

It has been recently suggested (1,2) that an electrical current flowing through a condueting medium can resonantly absorb energy from an oscillating magnetic feld, in a fashion similar to auclear inomeute in Nuclear Maguetic Resonance, giving rise to transient effects called free current decays and current echoes. We luve designed experimente to detect the Blectrical Current Resonance (ECR) in two dietinct yeters: to anetals and in an electron bear? In order to minimize the ellect of the skin-depth, thin films approximately 200.4 thick of Cu. Ag and Au have been grown for the experiment with toetal. The magnitude of the effect is estimated to be of a 10% for relaxation timen of a 1-2 as at 4.2 K. An AC field of a 20 gauss is produced by a pair of Helmholtz coite and applied perpendicularly to a static field, both on the plane of the sample. The resonance frequency Po (q/27m")Bo) is set between 0.5 and I GHa. The experimenta are carried out at 1.2 K. In a second experiment we try to observe PCH in an electron beam. The beam is generated in an Tektronix V859/1608 oscilloscope tube, Statie (H,) and oscillating (B,) Nelde are generated by two mutually perpendieular pairs of Helmbolte cone, with Ba 9 260 gause and 69 5 20 ganes. The mhomogoneity of the static told wan caleolated nimerically, The complete experimental setups and applications of the effect are discussed. We also discus possible connctions between KCK and the low-frequeney resonant modes in metals, knöwn as helicons: (4) I.S. Oliveira, A.P. Gromaries.and X. A. da Silva, Pbys, Rov, D50 (1997) in press (2) 1.5. Oliveira, Phys, Rev. Lett. 77 (1008) 139