Observation of a sharp lambda peak in the third harmonic voltage response of high-T $ \mathsf {_c}$ superconductor thin films

Cheenne, N.; Mishonov, Todor M.; Indekeu, Joseph

doi:10.1140/epjb/e2003-00125-4

Cited by 8 publications

(5 citation statements)

References 24 publications

(48 reference statements)

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“…If a constant or slowly varying electric field is used to detect nonlinear response, the large current will heat the sample during measurement, and spurious nonlinear contributions will appear if the resistance depends on temperature. Conventionally, millisecond field pulses are used to alleviate the heating problem, but heating still plays a role for highly conducting samples and needs to be disentangled from other possible contributions 65,66 . A pivotal step in our experiment is the use of a high-frequency excitation field—if the frequency is high enough, the time-dependent temperature change of bulk samples cannot follow the rapidly changing field, and no heating-induced nonlinear signal is observed.…”

Section: Methodsmentioning

confidence: 99%

Emergence of superconductivity in the cuprates via a universal percolation process

Pelc¹,

Vučković²,

Grbić³

et al. 2018

Nat Commun

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A pivotal step toward understanding unconventional superconductors would be to decipher how superconductivity emerges from the unusual normal state. In the cuprates, traces of superconducting pairing appear above the macroscopic transition temperature Tc, yet extensive investigation has led to disparate conclusions. The main difficulty has been to separate superconducting contributions from complex normal-state behaviour. Here we avoid this problem by measuring nonlinear conductivity, an observable that is zero in the normal state. We uncover for several representative cuprates that the nonlinear conductivity vanishes exponentially above Tc, both with temperature and magnetic field, and exhibits temperature-scaling characterized by a universal scale Ξ0. Attempts to model the response with standard Ginzburg-Landau theory are systematically unsuccessful. Instead, our findings are captured by a simple percolation model that also explains other properties of the cuprates. We thus resolve a long-standing conundrum by showing that the superconducting precursor in the cuprates is strongly affected by intrinsic inhomogeneity.

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Section: Methodsmentioning

confidence: 99%

Emergence of superconductivity in the cuprates via a universal percolation process

Pelc¹,

Vučković²,

Grbić³

et al. 2018

Nat Commun

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“…11,12 A significant problem, extensively discussed in literature, is the onset of nonlinear signals on account of fluctuations of sample temperature. 13,14 Any current passing through the sample inevitably causes heating, but if the current frequency is sufficiently high the sample temperature will not follow its oscillations -the heating will be uniform in time. The characteristic frequency where the current variation is too fast for the sample temperature to follow it is determined by the physical properties of the sample: FIG.…”

Section: A Low-power Measurementmentioning

confidence: 99%

Contactless measurement of nonlinear conductivity in the radio-frequency range

Došlić¹,

Pelc²,

Požek³

2014

Review of Scientific Instruments

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We have developed a system for contactless measurement of nonlinear conductivity in the radio-frequency band, and over a wide temperature range. A non-resonant circuit is used to electrically excite the sample, and the induced signal is detected by a resonant circuit whose natural frequency matches higher harmonics of the excitation. A simple modification of the probe allows non-resonant detection suitable for stronger signals. Two measurement procedures are proposed that allow significant excitation power variation, up to 150 W. The apparatus has been validated trough the measurement of the nonlinear response at the superconducting transition of a high-Tc superconductor, and the nematic transition of an iron pnictide.

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“…An analogous experimental research has been already performed for investigation of thermal interface resistance. 24 The suggested experiment can be done using practically the same experimental setup, only the gate electrodes should be added to the protected by insulator layer superconducting films.…”

Section: Determination Of Logarithmic Derivative Of Density Of Stmentioning

confidence: 99%

LCAO model for 3D Fermi surface of high-Tc cuprate Tl2Ba2CuO6+δ

Stoev

Mishonov

2009

Eur. Phys. J. B

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A simple analytical formula for three-dimensional Fermi surface (3D FS) of Tl2Ba2CuO 6+δ is derived in the framework of LCAO approximation spanned over Cu 4s, Cu 3d x 2 −y 2 , O 2px and O 2py states. This analytical result can be used for fitting of experimental data for 3D FS such as polar angle magnetoresistance oscillation. The model takes into account effective copper-copper hopping amplitude tss between Cu 4s orbitals from neighbouring CuO2 layers. The acceptable correspondence with the experimental data gives a hint that the tss amplitude dominates in formation of coherent 3D FS, and other oxygen-oxygen and copper-oxygen amplitudes are rather negligible. For absolute determination of the hopping parameters a simple electronic experiment with a field effect transistor type microstructure is suggested. The thin superconductor layer is the source-drain channel of the layered structure where an AC current is applied.

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Observation of a sharp lambda peak in the third harmonic voltage response of high-T $ \mathsf {_c}$ superconductor thin films

Cited by 8 publications

References 24 publications

Emergence of superconductivity in the cuprates via a universal percolation process

Emergence of superconductivity in the cuprates via a universal percolation process

Contactless measurement of nonlinear conductivity in the radio-frequency range

LCAO model for 3D Fermi surface of high-Tc cuprate Tl2Ba2CuO6+δ

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