A pulsed current set-up for use in magnetic fields above 30 T; application to high-temperature superconductors

Physical measurements of the normal state of an unconventional or high-temperature superconductor in the zero-temperature limit can provide vital information on the nature of the electronic ground state from which the superconductivity emerges. Viable routes to fully suppress the superconductivity include the application of magnetic fields stronger than the upper critical field <i>H_c</i>₂ or current densities larger than the critical current density <i>J_c</i>. In high<i>-T_c</i> superconductors, <i>H_c</i>₂ is typically higher than the available field strengths, while high currents can often create large heating effects that cause irreparable damage to the sample. Here, we present a technique that combines intense current pulses with high magnetic fields to fully suppress the superconductivity of a candidate high<i>-T_c</i> superconductor while keeping both <i>J</i> and <i>μ</i>₀<i>H</i> below their critical values. Two adaptable circuit designs are presented with negligible stray field or self-heating effects (below a critical current value). As a proof of principle, we apply the technique to a high<i>-T_c</i> cuprate with nominal <i>μ</i>₀<i>H_c</i>₂ ∼ 36 T and demonstrate the suppression of superconductivity down to <i>T/T_c</i> ≤ 0.1 in a field strength of just 24 T. Further applications of this dual technique are also discussed.