Effects of asymmetric splayed columnar defects on the anomalous peak effect in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$

Abstract

In order to enhance the critical current density ($J_c$) of superconductors, introduction of columnar defects (CDs) through swift-particle irradiation is effective. By dispersing the direction of CDs (splayed CDs), not only further enhancement of $J_c$ has been confirmed but also an anomalous peak effect (APE) in $J_c$ at a certain magnetic field determined by the irradiation dose was observed. It has been proposed that the APE arises from the suppression of kink motion and/or the effects of vortex entanglement in systems with splayed CDs. In this study, we measure $J_c$ properties of optimally K-doped Ba-122-type iron-based superconductor Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$ single crystals with splayed CDs that are introduced asymmetrically with respect to the $c$-axis by irradiating 2.6 GeV U ions. We discuss the significance of the average direction of splayed CDs to the APE. We also discuss the relationship between the APE and the entanglement of vortices.

arXiv comment19 pages, 7 figures, to be published in Journal of the Physical Society of Japan

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Cited by in corpus (3)

• Anisotropic physical properties and large critical current density in KCa${}_2$Fe${}_4$As${}_4$F${}_2$ single crystal
• A generalized phenomenological model for the magnetic field penetration and magnetization hysteresis loops of a type-II superconductor
• Crossover between Anomalous Peak Effects Induced by Splayed and Tilted Columnar Defects in Ba${}_{0.6}$K${}_{0.4}$Fe${}_2$As${}_2$