Stiffnessometer, a magnetic-field-free superconducting stiffness meter and its application

Abstract

We provide a detailed account for a new method to measure superconducting stiffness ${\rho }_s$, critical current density $j_c$, and coherence length $\xi$, in one apparatus, without subjecting the sample to magnetic field or attaching leads. The method is based on the London equation $\mathbf{j}=-{\rho }_s\mathbf{A}$, where $\mathbf{j}$ is the current density and $\mathbf{A}$ is the vector potential. Using a rotor free $\mathbf{A}$ and a measurement of $\mathbf{j}$ via the magnetic moment of a superconducting ring, we determine ${\rho }_s$. By increasing $\mathbf{A}$ until the London equation fails we determine $j_c$ and $\xi$. The method is sensitive to very small stiffness, which translates to penetration depth $\lambda \lesssim 1$~mm. It is also sensitive to low critical current density $j_c\sim 10^3$ Amm${}^{-2}$ or long coherence length $\xi \sim 1$~$\mu$m. Naturally, the method does not suffer from demagnetization factor complications, the presence of vortices, or out-of-equilibrium conditions. Therefore, the absolute values of the different parameters can be determined. We demonstrate the application of this method to La${}_{2-x}$Sr${}_x$CuO${}_4$ with $x=0.17$.

References in corpus (9)

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• Boundary states with elevated critical temperatures in Bardeen-Cooper-Schrieffer superconductors
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• The nature of the phase transition in the cuprates as revealed by a magnetic field free stiffness meter
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Cited by in corpus (9)

• Microscopic derivation of superconductor-insulator boundary conditions for Ginzburg-Landau theory revisited. Enhanced superconductivity at boundaries with and without magnetic field
• Boundary effects in two-band superconductors
• The nature of the phase transition in the cuprates as revealed by a magnetic field free stiffness meter
• Ginzburg-Landau model of a Stiffnessometer -- a superconducting stiffness meter device
• Elevated critical temperature at BCS superconductor-band insulator interfaces
• Stiffness and coherence length measurements of ultra-thin superconductor, and implications to layered superconductors
• Superconducting Stiffness and Coherence Length of FeSe${}_{0.5}$Te${}_{0.5}$ Measured in Zero-Applied Field
• Effect of medium on fundamental interactions in gravity and condensed matter
• The two critical temperatures conundrum in La${}_{1.83}$Sr${}_{0.17}$CuO${}_4$