Magnetic phase diagram and critical current of BaFe2As2 single crystals with hole- and electron-doping

11th European Conference on Applied Superconductivity

Pervakov, K.^1,2 ; Vlasenko, V.^1 ; Khlybov, E.^2,3 ; Pudalov, V.^1 ; Eltsev, Yu^1

P. N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow

119991, Russia^1

International Laboratory of High Magnetic Fields and Low Temperatures, Wroclaw

53-421, Poland^2

Institute for High Pressure Physics, Russian Academy of Sciences, Troitsk, Moscow region

142190, Russia^3

关键词: Ac-susceptibility measurements;    Irreversibility fields;    Irreversible magnetization;    Magnetic phase diagrams;    Strong magnetic fields;    Superconducting critical temperatures;    Temperature dependence;    Upper critical fields;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/507/1/012041/pdf
DOI  :  10.1088/1742-6596/507/1/012041

来源: IOP

【 摘 要 】

We report on comparative study of magnetic phase diagram and critical current of the hole- and electron-doped BaFe2As2single crystals with close values of superconducting critical temperature, Tc, (slightly underdoped Ba0.64K0.36Fe2As2with Tc=25K and optimally doped BaFe1.9Ni0.1As2with Tc=20K) obtained from measurements of the temperature dependence of ac-susceptibility and isothermal irreversible magnetization loops, M(H), in magnetic fields parallel to the c-axis of the crystal. From ac-susceptibility measurements we get estimation of a slope of the upper critical field, Hc2, in dependence on temperature, dHc2/dT -4.2T/K for BaFe1.9Ni0.1As2single crystal and Hc2/dT -1.75T/K for Ba0.64K0.36Fe2As2sample that in accordance with Werthamer, Helfand, and Hohenberg (WHH) model gives Hc2(0) 0.69Tc((dHc2)dT) 56T for BaFe1.9Ni0.1As2sample and lower value of Hc2(0) 31T for Ba0.64K0.36Fe2As2crystal. However, obtained from M(H) measurements temperature dependence of the irreversibility field, Hirr(T), for BaFe1.9Ni0.1As2crystal located below the one for Ba0.64K0.36Fe2As2crystal. Furthermore, at T=4.2K and higher temperatures our results for critical current density, Jc, calculated from M(H) curves clearly show slower reduction of Jcwith increasing field in even underdoped Ba0.64Ka0.36Fe2As2sample compared to optimally doped BaFe1.9Ni0.1As2crystal demonstrating higher capacity of K-doped 122 compounds for production of superconducting cables and wires with high critical current in strong magnetic fields.