D. J. Adelerhof

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The experimental sensitivity of double relaxation oscillation SQUIDs (DROSs) has been compared with theory and with the results obtained by numerical simulations. The experimental sensitivity ranges from 60 to 13h, where h is Planck's constant, for relaxation frequencies from 0.4 up to 10 GHz. For low frequencies the DROS characteristics can be explained by(More)
A process for fabricating high-quality Josephson junctions and DC SQUIDs on basis of Nb/Al technology has been developed. DC magnetron sputtering is used for the deposition of the metal layers and the barrier is formed by thermal oxidation of the Al-layer. The junction area of 5 microns x 5 microns is obtained using anodisation. Three types of Josephson(More)
A highly sensitive first-order gradiometer based on double relaxation oscillation SQUID's (DROS's) for multichannel use is presented. The white flux noise level of the bare DROS's is 4.5 /spl mu//spl Phi//sub 0///spl radic/Hz (/spl epsi/=275 h). With wire-wound first-order gradiometers, having a baseline of 40 mm, the white magnetic field noise equals 4(More)
The Nb/Al,AlO,(/Al)/Nb trilayer is deposited in a turbo pumped vacuum system. Nb and A1 films were deposited by two DC magnetron sputter guns at a rate of 200 nm/min and 22 nm/min, respectively. During sputtering the oxygen pressure was in the low lo-' mbar range. The water pressure was 10-7-10-8 mbar. The T, of the Nb films is 9.2 K. The trilayer(More)
Recently several approaches have been made to simplify the readout scheme of the standard dc SQUID. A double relaxation oscillation SQUID(DROS) consisting of a hysteretic dc SQUID and a reference junction in series shunted by an inductor and a resistor can provide a very large flux-to-voltage transfer coefficient. Thus, a DROS with direct readout with room(More)
Relaxation oscillation SQUIDs (ROSs) based on Nb/Al, AlO/sub x//Al/Nb Josephson tunnel junctions have been designed and fabricated. The hysteretic SQUIDs (superconducting quantum interference devices) have a maximum critical current of about 130 mu A and an inductance of 20 pH. A voltage modulation of 40 mu V and a flux to voltage transfer delta V/ delta(More)
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