1/f Noise in the superconducting transition of a MgB2 thin film

Lakew, B.; Aslam, Shahid; Jones, H. C.; Stevenson, Thomas; Cao, N.

doi:10.1016/j.physc.2010.03.009

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…Figure 8 shows the predicted D;b and or values for the bismuth and gold black coating i.e., ! !1 '" 3.1 X lOll crn/J and '" 4.8 x lOll cmll respectively, for comparison the theoretical '" for a 39K thermal detector operating at '" 1 0 Hz is 2.2 X 10constructed in this work is a factor of'" 46 away from what is theoretically possible and '" 2.5 from the findings of a previous paper [11] where it was predicted that an optimized phonon noise limited bolometer with aD;. -1.6 x 1011 cm'<'HzlW operating at 30Hz…”

Section: Space Matched and Gold Black Absorbermentioning

confidence: 54%

“…A 12.5 Y battery in series with a wire wound bias resistor (2.5 Mil) in a shielded box provides the low-noise constant current source. The effect of the bias circuit noise can be ignored when the bias resistor is much larger than the resistance of the bolometer at mid-point [11]. The cryostat dewar, Figure 2 shows R(T) transition curves for bolometer device #E4 operating in the constant current mode for two bias levels 1 ~A and 5 ~A.…”

Section: R(t) Ffi (F) and V (F) Measurementsmentioning

confidence: 99%

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MgB2 thin-film bolometer for applications in far-infrared instruments on future planetary missions

Lakew

Aslam

Brasunas

et al. 2012

Physica C: Superconductivity

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A SiN membrane based MgB2 thin-film bolometer, with a non-optimized absorber, has been fabricated that shows an electrical noise equivalent power of 256 fW /-.JHz operating at 30 Hz in the 8.5 -12.35 11m spectral bandpass. This value corresponds to an electrical specific detectivity of 7.6 x 10 10 cm-.JHzIW. The bolometer shows a measured blackbody (optical) specific detectivity of 8.8 x 10 9 cm-.JHzlW, with a responsivity of 701.5 kV/W and a first-order time constant of 5.2 rns. It is predicted that with the inclusion of a gold black absorber that a blackbody specific detectivity of 6.4 x 10 10 cm/-.JHzlW at an operational frequency of 10Hz, can be realized for integration into future planetary exploration instrumentation where high sensitivity is required in the 17 -250 11m spectral wavelength range.

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Section: Space Matched and Gold Black Absorbermentioning

confidence: 54%

Section: R(t) Ffi (F) and V (F) Measurementsmentioning

confidence: 99%

MgB2 thin-film bolometer for applications in far-infrared instruments on future planetary missions

Lakew

Aslam

Brasunas

et al. 2012

Physica C: Superconductivity

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“…[1][2][3][4] In particular, the dynamics of the resistive transition plays an important role in many applications, as, for instance, in the development of transition edge sensors (TES), used as radiation detectors. 5,6 The electrical noise is detected in specimens brought to a resistive state by varying temperature, current density with or without an applied magnetic field. Depending on the type of superconductive materials and on the experimental conditions, a stationary voltage noise can be generated either by magnetic flux flow under the action of a transversal current density, or by resistance fluctuation of the specimen brought to an intermediate state, constituted by a mixture of superconducting and resistive domains.…”

Section: Introductionmentioning

confidence: 99%

Dual stage resistive transition of MgB2 evidenced by noise analysis

Andreoli¹,

Carbone²,

Mazzetti³

et al. 2011

Journal of Applied Physics

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The resistive transition of polycrystalline superconducting MgB2 films is studied by means of an extensive set of stationary noise measurements, going from the very beginning of the transition to its final point, where the normal state is reached, either with and without magnetic field. The experimental results, taken at low current density and close to the critical temperature Tc, show very clearly the existence of two different dissipative processes at the different stages of the transition. An extended analysis proves that, at the beginning of the transition, when the resistance is below ten percent of normal value, the specimen is in a mixed state and dissipation is produced by fluxoid creation and motion. At higher temperature the specimen is in an intermediate state, constituted by a structure of interleaved superconducting and resistive domains. Such a situation occurs in type II superconductor when the transition temperature is very near to Tc and the critical field Hc for fluxoid penetration tends to zero. It is found that in the intermediate state, the power spectrum of the relative resistance fluctuations, is independent of the average resistance value and is unaffected by the magnetic field. As shown in the paper, this means that the noise is generated by density fluctuation of the normal electron gas in the resistive domains, while the contribution of the superconducting ones is negligible. The reduced noise amplitude does not depend on the steepness of the transition curve, thus adding further evidence to the above interpretation. The noise is thus related to the film impurities and can be investigated when the specimen is in the normal state, even at room temperature. The occurrence of a different dissipative process at low resistance is clearly evidenced by the experimental results, which show that the amplitude of the reduced power spectrum of the noise depends on magnetic field and resistance. These results are consistent with the assumption of fluxoid noise as shown by the model for the calculation of the noise developed in the manuscript.

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