Superconducting properties of Nb3Ge thin films prepared by coevaporation

Haeussler, E.; Saur, E.

doi:10.1007/bf00056651

Cited by 7 publications

(4 citation statements)

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“…Measurements by Haeussler and Saur have shown that the ratio of the critical parallel magnetic field to critical normal magnetic field is lower than predicted. 9 We find in our measurements that the slopes for the Nb0.7sGeo.22 system in parallel magnetic field have values ranging from 2.1 to 2.3 T/K for midpoint Tc's where Tc > 20.5 K. These values are comparable to reported values for sputtered films, of 2.24, 9'1~ 2.43, 6,7 and 2.5 T/K, 8 measured in perpendicular field.…”

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confidence: 79%

Magnetic field properties of 1 at.% transition metal substituted Nb3Ge

Cadieu

Chencinski

1980

J Low Temp Phys

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Measurements of the critical magnetic field slope near the superconducting transition temperature Tc are reported for samples of and (Nbo.99Zro.ol)l-xGex for 0.15<-x<-0.25. The samples investigated were produced by trisputtering onto heated polycrystalline alumina substrates. The critical magnetic field slope near Tc for substituted samples is comparable to that of Nb3Ge alone. The highest T~ values, the highest resistance ratios, and the narrowest transitions, however, occur for samples with excess transition metal component.We have previously reported the variation in the parallel critical field slopes dHez/dT near the zero-field, superconducting transition temperature Tc for (Nbo.99Ti0.01)l-xGex and (Nb0.99Zr0.ol)l_xGex. 1-3 The slopes previously reported were calculated using the onset transition temperature (the temperature that shows a change in slope from the normal state resistance versus temperature variation). The transition widths for these systems vary from -2 K at zero field to 4-6 K at 10 T. The slow variation of the resistance at the onset significantly contributes to the problems of determining the onset temperature. In Figs. 1-3 we present data to further characterize the variation of dHe2/dT near Tc in parallel field. The variation of dHc2/dT is given for five points along the superconducting transition: (1) the onset, (2) R =0.9RN, (3) R =0.5RN (midpoint), (4), R =0.1RN, (5) R =0 (zero electrical resistance), where RN is normal state electrical resistance.

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confidence: 79%

Magnetic field properties of 1 at.% transition metal substituted Nb3Ge

Cadieu

Chencinski

1980

J Low Temp Phys

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“…No strong columnar morphology is expected for evaporated Nb3Ge films, ~s they have been prepared at higher substrate temperatures than the sputtered films. 13 The differences in the structure of sputtered films has been shown to account for the differences in their superconducting properties. The same reason causes the observed superconducting properties of evaporated Nb3Ge films to differ from those observed for sputtered Nb3Ge.…”

Section: Discussionmentioning

confidence: 99%

“…Samples with dense columnar structure show higher critical fields in the parallel orientation, as has been observed in evaporated NbaGe films. 13 For samples with a more pronounced columnar structure, the critical induction has its maximum value for normal orientation of the magnetic field. In all cases the initial slope of Bc is between 2.2 and TemperGture Fig.…”

Section: Critical Inductionmentioning

confidence: 99%

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Superconducting properties of Nb3Ge thin films prepared by cosputtering

Braun

Saur

1978

J Low Temp Phys

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Nb3Ge films with thicknesses between 0.5 and 1.5 txm have been deposited on heated sapphire substrates by dc sputtering in a pure argon atmosphere. With a maximum superconducting onset temperature Tc = 22.7K, these high-To samples crystallize in a single-phase A15 structure with lattice parameters down to 5.14~. Critical current densities and upper critical magnetic inductions have been measured as a function of magnetic field orientation, temperature, and film thickness. The anisotropies of the critical currents and fields depend on the microstructure of the samples and show maxima for the field orientation normal to the sample surface in those films. that exhibit columnar growth of the crystallites normal to the substrate. The temperature, field, and angular dependences of the pinning forces in these films are compared to existing pinning theories.

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