Evolution of Critical Current Density in CaKFe$_4$As$_4$ with La-doping

Yangsong Chen; Chunlei Wang; Yuhang Zu; Yuto Kobayashi; Ataru Ichinose; Ryosuke Sakagami; Tsuyoshi Tamegai

doi:10.1088/1361-6668/ad8e00

paper

Evolution of Critical Current Density in CaKFe $_{4}$ As $_{4}$ with La-doping

arXiv:2412.03899 · doi:10.1088/1361-6668/ad8e00

Abstract

Single crystals of (Ca $_{1 - x}$ La $_{x}$ )KFe $_{4}$ As $_{4}$ (0 <= x <=0.16) have been grown by using the self-flux method, and the evolution of physical properties including the critical current density (Jc) with La-doping has been investigated. Tc decreases monotonically with increasing x, while Jc at the same temperature and magnetic field increases initially and reach its maximum at x = 0.082. The increase in Jc is more obvious at low temperatures and high fields. At T = 5 K and H = 40 kOe, Jc reaches 0.34 MA/cm $^{2}$ , which is ~4 times larger than that for pure crystals. It is also found that anomalous temperature dependence of Jc in CaKFe $_{4}$ As $_{4}$ is wiped away as the La content is increased. However, Jc shows non-monotonic field dependence (peak effect) at high fields in crystals with large x. In addition, we found that despite weak anisotropy of H $_{c 2}$ , there is extremely large anisotropy of Jc up to ~15, which is most likely caused by novel planar defects in the crystal, similar to CaKFe $_{4}$ As $_{4}$ . Jc characteristics in (Ca $_{1 - x}$ La $_{x}$ )KFe $_{4}$ As $_{4}$ with disorder outside FeAs planes is compared with that in CaK(Fe $_{1 - x}$ Co $_{x}$ ) $_{4}$ As $_{4}$ with disorder within FeAs planes.

12 pages, 8 figures, 1 table

Evolution of Critical Current Density in CaKFe4​As4​ with La-doping

Abstract

Evolution of Critical Current Density in CaKFe $_{4}$ As $_{4}$ with La-doping