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arXiv · 2007.13536

Effects of asymmetric splayed columnar defects on the anomalous peak effect in Ba$_{0.6}$K$_{0.4}$Fe$_{2}$As$_{2}$

Ayumu Takahashi·Sunseng Pyon·Tadashi Kambara·Atsushi Yoshida·Tsuyoshi Tamegai
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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.

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Ayumu Takahashi, Sunseng Pyon, Tadashi Kambara, Atsushi Yoshida, Tsuyoshi Tamegai. 2020-07-27. Effects of asymmetric splayed columnar defects on the anomalous peak effect in Ba$_{0.6}$K$_{0.4}$Fe$_{2}$As$_{2}$. https://doi.org/10.7566/jpsj.89.094705

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