Applied Physics Letters · 2004 · 14 citations · 7 references
Natural SciencesElectrical EngineeringPhysicsCondensed Matter PhysicsElectromagnetismMagnetic MaterialsMagnetic CharacterizationMagnetic Recording MaterialsMagnetic SensorsMagnetic Thin FilmsSuperconducting MaterialsSuperconducting Thin FilmsCommon-mode RejectionCommon-mode Rejection RatioMagnetic GradiometersMagnetic GradiometryQuantum InterferenceSquid MagnetometersSuperconducting Quantum Interference Device MagnetometryYttrium Barium Copper Oxide Films
We have fabricated single-layer, second-order high Tc superconducting quantum interference device (SQUID) gradiometers on SrTiO3 substrates and investigated their noise properties and performance in magnetocardiography. The gradiometer consists of three parallel pickup loops that are directly coupled to a step-edge junction SQUID, in such a way that the coupling polarity of two side loops is opposite to that of the center loop. The overall size of the device is 17.6 mm×6 mm with a baseline of 5.8 mm. The measured gradient noises are 0.45 and 0.84 pT/cm2/√Hz at 1 Hz for the shielded and the unshielded cases, respectively, which correspond to equivalent field noises of 150 and 280 fT/√Hz, respectively. In spite of the short baseline of 5.8 mm, the high common-mode rejection ratio of the gradiometer, 103, allowed us to record a magnetocardiogram of a human subject, which demonstrates the feasibility of the design in biomagnetic studies.
7
R. H. Koch, J. R. Rozen, Junjie Sun et al. · Applied Physics Letters · 1993 · 89 citations
Superconducting thin-film gradiometer
M. B. Ketchen, W. M. Goubau, John Clarke et al. · Journal of Applied Physics · 1978 · 86 citations
A second-order SQUID gradiometer operating at 77 K
Y. Tavrin, Y Zhang, Werner Wolf et al. · Superconductor Science and Technology · 1994 · 69 citations · Full text
A planar YBa2Cu3O7 gradiometer at 77 K
S. Knappe, D. Drung, T. Schurig et al. · Cryogenics · 1992 · 48 citations