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Resonant tunneling of fluctuation Cooper pairs.

Galda A, Mel'nikov AS, Vinokur VM - Sci Rep (2015)

Bottom Line: According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc.This striking effect offers an unprecedented tool for direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors.Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.

View Article: PubMed Central - PubMed

Affiliation: Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.

ABSTRACT
Superconducting fluctuations have proved to be an irreplaceable source of information about microscopic and macroscopic material parameters that could be inferred from the experiment. According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc. Here we report the current spikes due to radiation-induced resonant tunneling of fluctuation Cooper pairs between two superconductors which grow even sharper and more pronounced upon approach to Tc. This striking effect offers an unprecedented tool for direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors. Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.

No MeSH data available.


Related in: MedlinePlus

Smearing of resonant tunneling features by thermal voltage noise.Normalized tunneling current of fluctuation Cooper pairs as a function of V0 for various noise levels, Λ = 0(black), 1(blue), 5(green), 10(orange), 20(red), where we used the same system parameters as in Fig. 3a. White thermal voltage noise produces very little visible effect on the I–V characteristics of 1D junctions at , while higher values of the noise level parameter Λ cause smearing of the Shapiro resonances.
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f4: Smearing of resonant tunneling features by thermal voltage noise.Normalized tunneling current of fluctuation Cooper pairs as a function of V0 for various noise levels, Λ = 0(black), 1(blue), 5(green), 10(orange), 20(red), where we used the same system parameters as in Fig. 3a. White thermal voltage noise produces very little visible effect on the I–V characteristics of 1D junctions at , while higher values of the noise level parameter Λ cause smearing of the Shapiro resonances.

Mentions: Numerical analysis based on equation (8) in Methods for a typical junction with normal state resistance R ~ 10Ω shows that the effects of voltage fluctuations only become noticeable at temperatures as close to critical as , see Fig. 4. Even when the noise level parameter , the spikes on the I–V characteristics become only mildly smeared, with the features completely vanishing at . Therefore, the predicted effect of Shapiro spikes due to superconducting fluctuations is robust against thermal voltage noise and should be experimentally observable in a wide range of temperatures.


Resonant tunneling of fluctuation Cooper pairs.

Galda A, Mel'nikov AS, Vinokur VM - Sci Rep (2015)

Smearing of resonant tunneling features by thermal voltage noise.Normalized tunneling current of fluctuation Cooper pairs as a function of V0 for various noise levels, Λ = 0(black), 1(blue), 5(green), 10(orange), 20(red), where we used the same system parameters as in Fig. 3a. White thermal voltage noise produces very little visible effect on the I–V characteristics of 1D junctions at , while higher values of the noise level parameter Λ cause smearing of the Shapiro resonances.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4321188&req=5

f4: Smearing of resonant tunneling features by thermal voltage noise.Normalized tunneling current of fluctuation Cooper pairs as a function of V0 for various noise levels, Λ = 0(black), 1(blue), 5(green), 10(orange), 20(red), where we used the same system parameters as in Fig. 3a. White thermal voltage noise produces very little visible effect on the I–V characteristics of 1D junctions at , while higher values of the noise level parameter Λ cause smearing of the Shapiro resonances.
Mentions: Numerical analysis based on equation (8) in Methods for a typical junction with normal state resistance R ~ 10Ω shows that the effects of voltage fluctuations only become noticeable at temperatures as close to critical as , see Fig. 4. Even when the noise level parameter , the spikes on the I–V characteristics become only mildly smeared, with the features completely vanishing at . Therefore, the predicted effect of Shapiro spikes due to superconducting fluctuations is robust against thermal voltage noise and should be experimentally observable in a wide range of temperatures.

Bottom Line: According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc.This striking effect offers an unprecedented tool for direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors.Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.

View Article: PubMed Central - PubMed

Affiliation: Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.

ABSTRACT
Superconducting fluctuations have proved to be an irreplaceable source of information about microscopic and macroscopic material parameters that could be inferred from the experiment. According to common wisdom, the effect of thermodynamic fluctuations in the vicinity of the superconducting transition temperature, Tc, is to round off all of the sharp corners and discontinuities, which otherwise would have been expected to occur at Tc. Here we report the current spikes due to radiation-induced resonant tunneling of fluctuation Cooper pairs between two superconductors which grow even sharper and more pronounced upon approach to Tc. This striking effect offers an unprecedented tool for direct measurements of fluctuation Cooper pair lifetime, which is key to our understanding of the fluctuation regime, most notably to nature of the pseudogap state in high-temperature superconductors. Our finding marks a radical departure from the conventional view of superconducting fluctuations as a blurring and rounding phenomenon.

No MeSH data available.


Related in: MedlinePlus