IEEE Transactions on Instrumentation and Measurement · 1987 · 15 citations · 0 references
Natural SciencesElectrical EngineeringPhysicsCondensed Matter PhysicsElectromagnetismMagnetic MaterialsFerromagnetismMagnetic CharacterizationMagnetic Circuit AnalysisNoise In Electronic DevicesSuperconducting MaterialsCurrent NoiseNoise TemperatureSource ResistanceSquid MagnetometersTwo-dimensional Electron GasesTwo-dimensional Electron Systems
This paper describes theoretical and reproducible experimental results for a ferromagnetic-core (VITROVAC) flux transformer coupled SQUID instrument with equivalent noise temperatures < 1 K for 10-kΩ source resistance. The optimum dc current resolution of the superconducting transformer with and without a ferromagnetic core will be discussed. The high resolution of the SQUID instrument is demonstrated by the noise current plot and by noise temperature data of two-dimensional electron gases in GaAs-Ga <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1−x</inf> As heterostructures.