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Spin valve multilayers exhibiting enhanced giant magnetoresistive (GMR) effect and weak interlayer coupling as well as strong exchange biasing were fabricated by a two-step deposition procedure. The down sublayers (i.e., buffer layer Ta/free layer NiFe/interlayer Cu) were deposited at a lower argon pressure, then the upper sublayers (i.e., pinned layer NiFe/pinning layer FeMn/cover layer Ta) were deposited at a higher argon pressure. The former promoted formation of the strong (111) textures, smooth interfaces, and dense Cu film, resulting in a weak interlayer coupling. The latter promoted small domains and less diffusive interfaces, resulting in a strong exchange biasing and an enhanced GMR ratio. This shows that independent control of magnetoresistance, interlayer coupling, and exchange biasing is possible. (C) 1999 American Institute of Physics. [S0021-8979(99)06518-4].

Electrochemical gating permits the observation of few-atom processes in contact reconstruction. We monitor the junction conductance during the opening and closing of an atomic-scale metallic contact and use this as an instantaneous probe of the atomic-scale structural switching process. We observe clear correlations in the quantum conductance of a contact in subsequent switching events, demonstrating memory effects at the atomic scale. These experimental observations are supported by numerical simulations which show a conservation of the contact reconstruction process across several switching cycles. These results open a route to electrochemically control few-atom surface reconstruction events with present-day detection capabilities.