Vortex dynamics and second magnetization peak in the iron-pnictide superconductor Ca$_{0.82}$La$_{0.18}$Fe$_{0.96}$Ni$_{0.04}$As$_2$

I F Llovo; D Sóñora; J Mosqueira; S Salem-Sugui; Shyam Sundar; A D Alvarenga; T Xie; C Liu; S -L Li; H -Q Luo

doi:10.1088/1361-6668/ac2556

paper

Vortex dynamics and second magnetization peak in the iron-pnictide superconductor Ca $_{0.82}$ La $_{0.18}$ Fe $_{0.96}$ Ni $_{0.04}$ As $_{2}$

arXiv:2110.05677 · doi:10.1088/1361-6668/ac2556

Abstract

We report the studies of detailed magnetic relaxation and isothermal magnetization measurements in the vortex state of the 112-type iron-pnictide Ca $_{0.82}$ La $_{0.18}$ Fe $_{0.96}$ Ni $_{0.04}$ As $_{2}$ superconductor with $T_{c}$ $\sim$ 22 K. In the isothermal $M (H)$ , a well defined second magnetization peak (SMP) feature is observed in the entire temperature range below $T_{c}$ for measurements with $H$ $∥$ $c$ -axis. However, for $H$ $∥$ $ab$ -planes, the SMP feature is suppressed at low temperatures, which might be due to 2D Josephson vortices forming at low temperatures and high magnetic fields in such an anisotropic system. A rigorous analysis considering the magnetic relaxation data for $H$ $∥$ $c$ -axis suggests an elastic to plastic pinning crossover across $H_{p}$ , which also seems accompanied with a possible phase transition in vortex lattice near $H_{p}$ . Moreover, point disorder and surface defects are likely to be the dominant sources of pinning, which contribute to the $δ l$ -type of pinning in the sample. A high $J_{c}$ , in access of 10 $^{5}$ A/cm $^{2}$ observed could potentially make this material technologically important.

15 pages, 7 figures

Vortex dynamics and second magnetization peak in the iron-pnictide superconductor Ca0.82​La0.18​Fe0.96​Ni0.04​As2​

Abstract

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Vortex dynamics and second magnetization peak in the iron-pnictide superconductor Ca $_{0.82}$ La $_{0.18}$ Fe $_{0.96}$ Ni $_{0.04}$ As $_{2}$