Method to improve critical current density measurement of superconducting materials

The critical current density Jc is an important indicator of superconducting materials in practical applications. And the third harmonic voltage method is a simple, efficient and damage-free method for measuring Jc of hightemperature superconducting films. In order to more effectively measure the Jc of high-temperature superconducting REBa2Cu3O7-������films and improve the signal to noise ratio based on the third harmonic voltage method, a double-sided measurement method was hereby proposed. By integrating the electromagnetic shielding effect and the 2-coil measure-ment system, the Meissner effect was used to reduce the harmonic voltage noise in the pickup coil. Comparing the double-sided measurement system using the new method to the 2-coil mea-surement system, the signal-to-noise ratio increases by 10 dB to 20 dB in the case of a Jc measured in the frequency range from 100 Hz to 1000 Hz. The bullet points of the method can be listed as: & BULL; The noise in the pickup coil is reduced and the signal-to-noise ratio is improved in the fre-quency range from 100 Hz to 1000 Hz by using the Meissner effect.& BULL; The measurement bandwidth is increased, making it possible to conduct low-frequency mea-surement in the future by the double-sided measurement method.& BULL; The method provides an improvement direction for superconducting thin films with a high critical current density in the future.