Influence of magnetic ordering on the vortex matter in RbEuFe<sub>4</sub>As<sub>4</sub> single crystals
ORAL
Abstract
Eu-containing Fe-based superconductors are ideal systems to study the interplay of superconductivity and magnetic order. The superconductor RbEuFe4As4 has Tc~37K and undergoes a magnetic ordering of the Eu at Tm~15K. We studied vortex pinning and dynamics in RbEuFe4As4 single crystals as a function of temperature (T), magnetic field and orientation (Θ) by angular dependent magnetization. The critical current density (Jc) of the pristine crystals is low, indicative of small disorder, and weakly anisotropic. Introduction of aligned columnar defects (CDs) by heavy ion irradiation increases Jc, but produces almost no changes in Tc and Tm. In the crystals with CDs, Jc(Θ) exhibits a lockin phase, the fingerprint of correlated pinning. Both pristine and irradiated crystals show clear evidence of the influence of the magnetic order on the vortex matter. In pristine crystals, the rate of decrease in Jc with T slows down in the proximity of Tm. Irradiation enhances this effect, with Jc(T) becoming nonmonotonic and developing a local maximum near Tm. In both cases, flux creep rates exhibit local minima around the magnetic transition, indicating an increase in the vortex pinning energy.
*Work supported by U.S. DOE, Office of Basic Energy Sciences, Materials Sciences and Engineering Division.
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Presenters
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Leonardo Civale
- MPA-Condensed Matter and Magnet Science, Los Alamos National Laboratory