Plastic pinning replaces collective pinning as the second magnetization peak disappears in the pnictide superconductor Ba-KFe${}_2$As${}_2$

Abstract

We report a detailed study of isofield magnetic relaxation and isothermal magnetization measurements with $H$$\parallel$c on an underdoped Ba${}_{0.75}$K${}_{0.25}$Fe${}_2$As${}_2$ pnictide single crystal, with superconducting transition temperature $T_c$ = 28 K. The second magnetization peak (SMP) has been observed at temperatures below $T_c$/2 and vanished at higher temperatures. The observed behaviour of the SMP has been studied by measuring the magnetic field dependence of relaxation rate, $R(H)$ and by performing the Maley's analysis. The results suggest that the crossover from collective to plastic pinning observed in the SMP disappears above 12 K with plastic pinning replacing collective pinning. An interesting $H$-$T$ phase diagram is obtained. The critical current density ($J_c$) was estimated using Bean's model and found to be $\sim$ $3.4\times 10^9$ A/m${}^2$ at 10 K in the SMP region, which is comparable to an optimally doped Ba-KFe${}_2$As${}_2$ superconductor and may be exploited for potential technological applications. The pinning mechanism is found to be unconventional and does not follow the usual $\delta l$ and $\delta T_c$ pinning models, which suggest the intrinsic nature of pinning in the compound.

8 pages, 9 figures

References in corpus (13)

• Nearly Isotropic superconductivity in (Ba,K)Fe2As2
• Upper critical fields and thermally-activated transport of Nd(O_0.7F_0.3)FeAs single crystal
• Advantageous grain boundaries in iron pnictide superconductors
• High intergrain critical current density in fine-grain (Ba0.6K0.4)Fe2As2 wires and bulks
• Determination of anisotropic Hc2 up to 60 T in (Ba0.55K0.45)Fe2As2 single crystals
• Upper critical fields well above 100 T for the superconductor SmFeAsO${}_{0.85}$F${}_{0.15}$ with T${}_c$ = 46 K
• Growth and characterization of A_{1-x}K_xFe_2As_2 (A = Ba, Sr) single crystals with x=0 - 0.4
• Biaxially textured cobalt-doped BaFe2As2 films with high critical current density over 1 MA/cm2 on MgO-buffered metal-tape flexible substrates
• High Critical Current Density 4 MA/cm2 in Co-Doped BaFe2As2 Epitaxial Films Grown on (La, Sr)(Al, Ta)O3 Substrates without Buffer Layers
• High transport Jc in magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process
• Experimental observation of an anomalous peak in isofield M(T) curves in BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$ resembling the fish-tail in $M$($H$) curves further suggesting a possible phase transition in the irreversible regime
• Magnetic irreversibility and pinning force density in the Mo${}_{100-x}$Re${}_x$ alloy superconductors
• Vortex dynamics as a function of field orientation in BaFe1.9Ni0.1As2

Cited by in corpus (3)

• Comparative study of vortex dynamics in CaKFe4As4 and Ba0.6K0.4Fe2As2 single crystals
• Study of the second magnetization peak and the pinning behaviour in Ba(Fe${}_{0.935}$Co${}_{0.065}$)${}_2$As$_2
• Strong pinning in the hole-doped pnictide superconductor La${}_{0.34}$Na${}_{0.66}$Fe${}_2$As${}_2$