Open AccessReemergence of superconductivity by 4d transition-metal Pd doping in over-doped 112-type iron pnictide superconductors Ca0.755La0.245FeAs2
Author(s) -
Xiangzhuo Xing,
Zhanfeng Li,
I. S. Veshchunov,
Xiaolei Yi,
Yan Meng,
Meng Li,
Bing Lin,
T. Tamegai,
Zhixiang Shi
Publication year - 2019
Publication title -
new journal of physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.584
H-Index - 190
ISSN - 1367-2630
DOI - 10.1088/1367-2630/ab3d75
Subject(s) - superconductivity , doping , antiferromagnetism , tetragonal crystal system , condensed matter physics , orthorhombic crystal system , pnictogen , phase diagram , physics , crystallography , transition metal , electrical resistivity and conductivity , phase (matter) , crystal structure , chemistry , biochemistry , quantum mechanics , catalysis
In 112-type iron-based superconductors (IBSs), rare earth (e.g. La) doping enhanced antiferromagnetic (AFM) order and 3 d transition-metal (e.g. Co, Ni) doping induced reemergence of superconductivity (SC) in the over-doped regime (non-SC) are of particular interest, providing a significant opportunity to further understand the relationship between SC and AFM order in IBSs. Recently, 4 d transition-metal Pd-doped 112-type Ca 1- y La y Fe 1- x Pd x As 2 ( x > 0.2, 0 ≤ y ≤ 0.3) compounds, which crystallized in new orthorhombic and tetragonal structures, have been identified ( Inorg. Chem. 56 3030 (2017)). However, none of them exhibit SC, probably due to the oversubstitution of Pd for Fe. Here, to reveal the impact of slight Pd doping on the over-doped Ca 1- y La y FeAs 2 and compare to 3 d Co/Ni doping series, single crystals of Ca 0.755 La 0.245 Fe 1- x Pd x As 2 with 0 ≤ x ≤ 0.08 are successfully grown using the self-flux method. We find that, upon only a small amount of Pd doping ( x = 0.013), bulk SC with a maximum T c of 28.5 K is reemerged, in contrast to the case with high Pd doping level. Moreover, based on the electrical resistivity and magnetization data, we construct the temperature-composition ( T – x ) phase diagram, the shape of which, particularly for the region where the AFM and SC phases coexist microscopically, is almost identical to that of Ca 0.76 La 0.24 Fe 1- x Ni x As 2 , but is distinctly different from that of Ca 0.74 La 0.26 Fe 1- x Co x As 2 , presumably due to the presence of complex doping mechanism in 112-type IBSs. Finally, for one selected single crystal with x = 0.013, superconducting properties including critical current density, vortex pinning mechanism, and vortex diagram are systematically studied by magnetization, magneto-optical imaging, and magneto-resistivity measurements. Our work provided more insight into the phase diagrams and superconducting properties of 112-type IBSs, allowing better understanding of its superconducting mechanism and developing the potential applications.