Optical and electrical changes of hydrogenated Dy films

Electrical and optical measurements on hydrogenated Pd coated (20 nm) Dy fi lms (250-300 nm) are presented. The films are prepared in a high vacuum cha mber and hydrogenated, at room temperature, by exposing them to a hydrogen atmosphere. Maximum hydrogen concentration of the order of 3 is achieved as measured by QCM. Changes in electrical resistance and optical transmission (at lambda=632.8 nm) in the films indicate the dielectric nature of the Dy H3. The Hall coefficient measured also as a Function of concentration, give s an insight into the evolution of the density of charge carriers as hydrog en is absorbed. (C) 2000 Elsevier Science S.A. All rights reserved.