On the response time of YBa2Cu3O7 superconducting bolometer films

Maneval, J. P.; Hong, Khôi Phan; Chibane, F.

doi:10.1016/0921-4534(94)91221-1

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…The results of the present work (t 6.5 and 2 ns, respectively, for 75 and 30 nm films) compare very well with determinations of t g based on the decay of photoinduced resistance in similar YBCO-on-MgO films (4 ns for a 48 nm film [12] up to 81 K; 2.4 ns for a 30 nm film [14] throughout the range 1.3 to 50 K). Sample LZCYB-77 (35 nm), with a comparatively large t 5 ns, is no contradiction since it comprises two matching layers between film and substrate.…”

supporting

confidence: 71%

“…Therefore, we believe gap relaxation is limited not by intrinsic relaxation mechanisms, but rather by the rate of phonon removal from the film, so that film cooling actually sets the pace of gap relaxation [11]. In the case of epitaxial YBCO on a crystalline substrate, several authors [12][13][14] have independently measured cooling times (a) proportional to film thickness and (b) independent of T practically up to T c . Theoretically, such properties derive from the phonon radiation model, so called with reference to the optical blackbody, according to which the power transferred goes as T 4 (Stefan's law), in proportion to the lattice energy R…”

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confidence: 99%

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Time of Nucleation of Phase-Slip Centers inYBa2Cu3O7Superconducting Brid

et al. 1998

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Narrow YBa 2 Cu 3 O 7 films, excited by pulses of supercritical current, had their nanosecond electric response monitored in zero applied magnetic field. Delayed voltage steps plus constant differential resistance, characteristic of phase-slip centers (PSC), are observed at all temperatures. The duration of the initial zero voltage state is well fit by Ginzburg-Landau based theories, with a gap relaxation time controlled by phonon escape. At higher levels of excitation, PSC's give birth to slowly spreading normal hot spots. [S0031-9007(98)06897-5] PACS numbers: 74.76. Bz, 74.25.Kc, 74.40. + k, 74.50. + r Superconductivity is perturbed, not suppressed, by a critical current. Thanks to vortex motion, the growing phase differences of the order parameter wave function relax by multiples of 2p [1], a process which allows the material to preserve long range order while sustaining a voltage. In filamentary structures, similar quantum phase jumps occur in short, fixed, zones named phaseslip centers [2] (PSC). So, dissipation arises in a way fundamentally different from a transition into the normal state. A second singular feature is the long persistence of the zero voltage state after the application of the supercritical current, much beyond the natural (picosecond) time h͞D (Planck constant divided by the energy gap). Pals and Wolter [3] discovered this delay, or PSC nucleation time, t d on aluminum film strips. Interpreting it as the time required to achieve complete collapse of the order parameter, and using a timedependent Ginzburg-Landau (TDGL) equation based on the nonequilibrium energy-mode gap relaxation time [4], they could account fairly for their experimental data.It would be difficult to make any predictions for cuprate superconductors, due to their utterly short coherence length. Nevertheless, the dc current-voltage ͑I-V ͒ curves of high-T c narrow bridges indeed display the steps and the expected response to microwave radiation [5] related to PSC's. This Letter reports on the first observation of the delay t d in epitaxial YBa 2 Cu 3 O 7 thin films, and its interpretation through TDGL. At the same time, we tackle directly the troublesome problem of heating in a dissipative center.Our experiments were performed in zero applied magnetic field on c-axis textured films with typical misorientation 0.5 degree of arc. Sample LL-109N is a 75 nm thick film evaporated [6] on ͓100͔ MgO with cationic composition YBa 1.88 Cu 3.04 . Our bridge has resistivity r͑300 K͒ 350 mV cm, a ratio RRR r͑300 K͒͞r͑100 K͒ 2.8, and a critical temperature T c 89 K. Samples TO-34 and TO-S35, obtained by dc hollow cathode sputtering [6], had similar electrical characteristics. Finally, sample LZCYB77 is a 35 nm thick film deposited by laser ablation [6] on ͓100͔ Si covered with a buffer layer (70 nm YSZ; 10 nm CeO 2 ). Our bridge had r͑300 K͒ 1.9 mV cm, and RRR 2.6.According to the standard PSC model [7], each phaseslip event produces a burst of quasiparticles, whose diffusion eventually determines the length of the dissipative zone. T...

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confidence: 71%

mentioning

confidence: 99%

Time of Nucleation of Phase-Slip Centers inYBa2Cu3O7Superconducting Brid

et al. 1998

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“…We constructed junction legs so that the heat and electron transport is towards the cold end in the plane of the film. This is in contrast to the structure used by others [1][2][3][4][5] where the heat transfer was downward towards the substrate under the film, with often buffer layers in-between. The objective of this work is to investigate properties of HTSC-Bi-based devices for both thermal and optical radiation detection on the one hand and temperature (near 77 K) control over small areas on the other.…”

Section: Introductionmentioning

confidence: 58%

“…One of the most promising outcomes from the discovery of high-temperature superconductors is the ability to develop high sensitivity HTSC-semiconductor sensors of electromagnetic radiation at liquid nitrogen temperatures. One can make devices purely bolometric [1] in nature which have a relatively slow response or much faster non-bolometric ones [2,3] where the response time is paramount. Alternately, one can pass current through the junction and use it as a thermoelectric device controlling the temperature at the junction.…”

Section: Introductionmentioning

confidence: 99%

Photo-thermal electron transport in YBCO - bismuth junctions

Kaila¹,

Cochrane²,

Russell³

1997

Supercond. Sci. Technol.

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Electron transport analysis of photo-thermal studies carried out using a 10 mW He-Ne laser and YBCO-bismuth thick (50 µm) film junctions is presented. In single stage geometry a 50 mV photo-voltage develops across the junction at 77 K with a bias current of 15 mA. A 0.08 K −1 temperature coefficient of resistance was found over the superconducting to normal state transition (80-90 K) for the junction which leads to a responsivity of 5 V W −1 . In a two stage thermopile cascade configuration a thermoelectric voltage of 20 mV was found which corresponds to a temperature difference of 0.25 • C between the hot and cold ends at 77 K.

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