Ultrasensitive Potentiometer for Use at Liquid Helium Temperatures

McWane, J. W.; Neighbor, J. E.; Newbower, Ronald S.

doi:10.1063/1.1720052

Cited by 34 publications

(5 citation statements)

References 2 publications

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“…1 is similar to that of McWane et al (1966), but includes a few modifications which allow greater accuracy. * In operation the values of the biasing currents I, and Ij are adjusted to obtain a suitable operating point for the slug with the feedback loop open circuit.…”

Section: Measurementsmentioning

confidence: 97%

Anisotropy in the Kondo effect of single crystal Zn–Mn alloys

Muir¹,

Stroink²,

Wassermann³

1977

Can. J. Phys.

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The anisotropy in the Kondo effect of single crystal ZnMn alloys (10-500 at. ppmMn) has been studied between 0.3 and 8 K. The impurity resistivity with current flowing perpendicular to the c-axis of the hexagonal crystal is 1.6 times greater than the impurity resistivity with the current flowing parallel to the c-axis for all the ZnMn alloys. The resistivity of a Zn 500 at. ppm Al alloy was found to be isotropic and, in agreement with previous results, the resistivity of pure zinc was found to be nearly isotropic. On the basis of a two band model for zinc we show that the ratio the relaxation time on the monster and lens portions of the Fermi surface T L / r M is 1.3 ? 0.1 for pure Zn, 1. l 1+_ 0.3 for the ZnAl alloy, and 0.43 1+_ 0.05 for the ZnMn alloys. We attribute the threefold variation of T M I T~ between magnetic Mn (11-type) impurities and the nonmagnetic (s,p-type) impurities in pure Zn and the ZnAl alloys to the nature of the conduction electron wave functions on the monster and lens portions of the Fermi surface of Zn. We require the partial density of s,p-like wave functions to 1.2 times greater on the lens surface than on the monster surface while the partial density of (/-like wave functions on the lens surface must be 0.4 times their density on the monster surface.On aetudik I'anisotropie de I'effet Kondo dans des monocristaux d'alliages ZnMn (10-500 ppm at. Mn) entre 0.3 et 8 K. La rksistance due aux impuretks, pour un courant perpendiculaire a I'axe c du cristal hexagonal, est 1.6fois plus grande que pour un courant parallele BI'axe c. dans tous les alliages ZnMn. On trouve que la resistivitk d'un alliage Zn 500 ppm at. Al est isotrope et que celle du zinc pur, en accord avec des rksultats antkrieurs. est presque isotrope. Sur la base d'un modele a deux bandes pour le zinc, nous montrons que le rapport des temps de relaxation sur la portion monstre et la portion lentille de la surface de Fermi, r L / T M est 1.3 2 0. I pour Zn pur, 1.1 t 0.3 pour I'alliage ZnAl et 0.43 L 0.05 pour les alliages ZnMn. Nous attribuons la variation de 7~1~~ parun facteur trois, entre le cas des impuretks magnktiques Mn (de type tl) et celui des impuretes non mangktiques (de type s,p) dans le Zn pur et les alliages ZnAl a la nature des fonctions d'onde des electrons de conduction sur les portions monstre et lentille de la surface de Fermi de Zn. I1 faut que la densite partielle des fonctions d'onde de type s.p soit 1.2fois plus grande sur la surface lentille que sur la surface monstre, et que la densite partielle de fonctions d'onde de type tl soit sur la surface lentille 0.4de ce qu'elle est sur la surface monstre.[Traduit par le journal]Can. J. Phys.. 55,403 (1977)

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Section: Measurementsmentioning

confidence: 97%

Anisotropy in the Kondo effect of single crystal Zn–Mn alloys

Muir¹,

Stroink²,

Wassermann³

1977

Can. J. Phys.

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“…A note on nomenclature: a number of schemes have been developed for reading out SQUIDs. Because this report focuses on software developed for the STARCryo PCI-1000/PFL-100/PFL-102 SQUID electronics, we will sometimes use "modulation" as shorthand for the PFL-100 flux-modulation flux-locked-loop (FLL) electronics reading out a single dc SQUID, and "array" or "two-stage" as shorthand for the PFL-102 two-stage SQUID FLL electronics using directly-coupled readout [14] [15], with a single dc SQUID as the first stage, and a STARCryo SQUID array as the second stage [16].…”

Section: Introductionmentioning

confidence: 99%

OpenSQUID: A Flexible Open-Source Software Framework for the Control of SQUID Electronics

Jaeckel

Lafler

Boyd

2013

IEEE Trans. Appl. Supercond.

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Commercially available computer-controlled SQUID electronics are usually delivered with software providing a basic user interface for adjustment of SQUID tuning parameters, such as bias current, flux offset, and feedback loop settings. However, in a research context it would often be useful to be able to modify this code and/or to have full control over all these parameters from researcher-written software. In the case of the STAR Cryoelectronics PCI/PFL family of SQUID control electronics, the supplied software contains modules for automatic tuning and noise characterization, but does not provide an interface for user code. On the other hand, the Magnicon SQUIDViewer software package includes a public application programming interface (API), but lacks auto-tuning and noise characterization features. To overcome these and other limitations, we are developing an "open-source" framework for controlling SQUID electronics which should provide maximal interoperability with user software, a unified user interface for electronics from different manufacturers, and a flexible platform for the rapid development of customized SQUID auto-tuning and other advanced features. We have completed a first implementation for the STAR Cryoelectronics hardware and have made the source code for this ongoing project available to the research community on SourceForge (http://opensquid.sourceforge.net) under the GNU public license. 

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“…In the limit LU << fl LC, the current amplification becomes A = Nkcp· (14) In this limit the effective inductance may be wTitten from Eqs. (6), (11), and (14) as (15) If LC >> LU, this result follows even for fl = 1 and there is little to be gained by using a high permeability core.…”

Section: Ucrl-20360mentioning

confidence: 99%

Impedance Matching a Josephson Galvanometer by Means of a Superconducting Transformer

Clarke

Tennant

Woody

1971

Journal of Applied Physics

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The concept of an effective noise temperature is developed and applied to superconducting galvanometers. It is shown that even when the device is being used at a temperature above its noise temperature, Johnson noise in a source resistance may be observed only if this resistance is below a certain value, defined as the critical resistance. A detailed design is given for a superconducting transformer which matches the galvanometer to higher resistance and thereby appreciably increases the critical resistance. The transformer may be used at zero frequency. A practical transformer is described which has been used with the Josephson device known as the Slug. The transformer increased the critical resistance from 7×10−8 to 2×10−2 Ω and could be readily adapted to match to resistances up to 1 Ω.

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Ultrasensitive Potentiometer for Use at Liquid Helium Temperatures

Cited by 34 publications

References 2 publications

Anisotropy in the Kondo effect of single crystal Zn–Mn alloys

Anisotropy in the Kondo effect of single crystal Zn–Mn alloys

OpenSQUID: A Flexible Open-Source Software Framework for the Control of SQUID Electronics

Impedance Matching a Josephson Galvanometer by Means of a Superconducting Transformer

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