Transition to the normal state induced by high current densities in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>YBa</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mtext>Cu</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mtext>O</mml:mtext><mml:mrow><mml:mn>7</mml:mn><mml:mo>−</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>thin films: A thermal runaway account

Maza, J.; Ferro, Gonzalo; Veira, J.A.; Vidal, F.

doi:10.1103/physrevb.78.094512

“…Within this assumption, it is possible to employ the functional form suggested in Ref. [12] to fit experimental data at low bias above the critical current I c . In this regime, the measured I-V characteristics are indeed well described by the isothermal curves…”

Section: Methodsmentioning

confidence: 99%

Competition between intrinsic and extrinsic effects in the quenching of the superconducting state in Fe(Se,Te) thin films

Leo

¹

,

Marra

²

,

Grimaldi

³

et al. 2016

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We report the first experimental observation of the quenching of the superconducting state in current-voltage characteristics of an iron-based superconductor, namely, in FeSeTe thin films. Based on available theoretical models, our analysis suggests the presence of an intrinsic flux-flow electronic instability along with non-negligible extrinsic thermal effects. The coexistence and competition of these two mechanisms classify the observed instability as halfway between those of low-temperature and of high-temperature superconductors, where thermal effects are respectively largely negligible or predominant.

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“…(1) to roughly estimate that if the superconducting bridge had A b /A s one thousand times larger, as it is the case of those currently proposed for high power applications [1,17], DT b would take values at least two orders of magnitude higher. To confirm these values at a quantitative level, DT b has been calculated by using a finite element method similar to the one described in [13]. Under the same conditions as above, for the BS7 microbridge we found again DT b % 0:1 K.…”

Section: Introductionmentioning

confidence: 92%

“…However, the current is effectively limited only for electric fields or, equivalently, applied voltages well above that at which the limiter is triggered from normal operation (sample in the superconducting state) to current fault mode. In addition, once J * is attained, a thermal runaway [12,13] can be provoked which causes the reduction of the circulating current well below the nominal value (i.e., the current in normal operation without a fault) or very important damage on the microbridge (that can be even burnt out).…”

Section: Introductionmentioning

confidence: 98%

“…However, the current is effectively limited only for electric fields or, equivalently, applied voltages well above that at which the limiter is triggered from normal operation (sample in the superconducting state) to current fault mode. In addition, once J * is attained, a thermal runaway [12,13] can be provoked which causes the reduction of the circulating current well below the nominal value (i.e., the current in normal operation without a fault) or very important damage on the microbridge (that can be even burnt out).The superconducting microbridge exchanges heat mainly with its substrate, because at the operation temperatures, around 90 K, the heat transfer coefficient between YBCO films, for instance, and their substrate is h bs % 10 3 W cm À2 K, whereas through liquid nitrogen or between the substrate and the copper holder (h sr ) they are 1000 times less [9,14,15]. Hence, the conditions for a good refrigeration and, therefore, an optimal operation of the limiting device, depend very much on the relative dimensions of the microbridge and their substrate.…”

mentioning

confidence: 99%

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Thermal behaviour of high-temperature superconducting fault current limiters: Application to microlimiters

Lorenzo-Fernández

¹

,

Osorio

²

,

Veira

³

et al. 2010

Journal of Physics and Chemistry of Solids

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a b s t r a c tFault current limiters are one of the most promising applications of high-temperature superconductors. Two important and interrelated aspects of these devices are their thermal behaviour and their refrigeration. Here we will present some results of our recent researches about this topic concerning the possibility of using superconducting thin-film microbridges as very efficient microlimiters intended to operate at very low powers as could be superconducting microelectronics applications (SQUID based electronics, infrared detectors, etc.).& 2010 Published by Elsevier Ltd.Superconducting fault current limiters (SFCL) based on high temperature superconductors (HTSC) of different types, inductive, resistive or hybrid (i.e. inductive-resistive), have being extendedly studied [1][2][3][4][5][6][7]. The refrigeration and thermal behaviour of the superconducting elements are aspects of crucial importance for the overall performance of these devices. Thin film samples present several advantages to be used in current limiting applications [4,8,9]. We have studied the use of this kind of samples in two up to now nearly unexplored configurations. One is a hybrid limiting device based on meandered HTSC thin-films refrigerated by using a thermoacoustic refrigerator [10], and the other a resistive FCL based on ''thermally small'' superconducting microbridges [9] intended to operate at very low powers (SQUID based electronics, infrared detectors, etc.). In this work we will summarize some of our recent results on this last issue.In Fig. 1 we show a typical electric field versus current density (EÀ J) curve, corresponding to one of the microbridges (denoted BS7) used in our experiments. This microbridge, whose length, width and thickness are, respectively, 385 mm, 28 mm and 300 nm, and with T c ¼ 88.6 K, has been grown on a sapphire substrate. The two characteristic current densities are indicated in this figure:The critical, J c , at which dissipation first appears, and the so-called supercritical, J * , at which the microbridge is triggered into highly dissipative states. Let us note here that we have chosen for our studies microbridges of these dimensions to guarantee a good thermal behaviour before, during and after the current fault, as we will see below. In addition, the widths of our microbridges are well above the threshold at which J * is sample-width dependent [11]. The strong increase of E for current densities around J * make this type of samples very useful for FCL. However, the current is effectively limited only for electric fields or, equivalently, applied voltages well above that at which the limiter is triggered from normal operation (sample in the superconducting state) to current fault mode. In addition, once J * is attained, a thermal runaway [12,13] can be provoked which causes the reduction of the circulating current well below the nominal value (i.e., the current in normal operation without a fault) or very important damage on the microbridge (that can be even burnt out).The superconducting ...

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“…However, the current is effectively limited only for electric fields or, equivalently, applied voltages well above that at which the limiter is triggered from normal operation (sample in the superconducting state) to current fault mode. In addition, once J * is attained, a thermal runaway (Viña et al, 2003;Maza et al, 2008) can be provoked which causes the reduction of the circulating current well below the nominal value (i.e., the current in normal operation without a fault) or very important damage on the microbridge (that can be even burnt out).…”

Section: Superconducting Fault Current Microlimitersmentioning

confidence: 99%

Thermal Behaviour and Refrigeration of High-Temperature Superconducting Fault Current Limiters and Microlimiters

Veira¹,

Osorio²,

Vidal³

2012

Superconductors - Properties, Technology, and Applications

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0

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Transition to the normal state induced by high current densities inYBa2Cu3O7−δthin films: A thermal runaway account

Cited by 26 publications

References 50 publications

Competition between intrinsic and extrinsic effects in the quenching of the superconducting state in Fe(Se,Te) thin films

Competition between intrinsic and extrinsic effects in the quenching of the superconducting state in Fe(Se,Te) thin films

Thermal behaviour of high-temperature superconducting fault current limiters: Application to microlimiters

Thermal Behaviour and Refrigeration of High-Temperature Superconducting Fault Current Limiters and Microlimiters

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