Coexistence of Long-Range Magnetic Order and Superconductivity from Campbell Penetration Depth Measurements

Abstract

Application of a tunnel-diode resonator (TDR) technique for studies of the vortex response in magnetic superconductors is described. Operating at very small excitation fields and sufficiently high frequency, TDR was used to probe small-amplitude linear AC response in several types of single crystals where long-range magnetic order coexists with bulk superconductivity. Full local - moment ferromagnetism destroys superconductivity and can coexist with it only in a narrow temperature range ($\sim 0.3$ K). In contrast, weak ferromagnetic as well as antiferromagnetic orders can coexist with bulk superconductivity and may even lead to enhancements of vortex pinning. By analyzing the Campbell penetration depth we find sharp increase of the true critical current in the vicinity of the magnetic phase transitions. We conclude that critical magnetic fluctuations are responsible for this enhancement.

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Cited by in corpus (4)

• Enhanced critical current density in the pressure-induced magnetic state of the high-temperature superconductor FeSe
• Campbell penetration depth in low carrier density superconductor YPtBi
• Strong Enhancement of the Critical Current at the Antiferromagnetic Transition in ErNi2B2C Single Crystals
• Effect of controlled artificial disorder on the magnetic properties of EuFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$ ferromagnetic superconductor