Electrical and Thermal Transport Properties of Layered Superconducting Ca10(Pt4As8)((Fe0.86Pt0.14)2As2)5 Single Crystal

Abstract

We have synthesized single crystals of iron-based superconducting Ca10(Pt4As8)((Fe0.86Pt0.14)2As2)5 and performed extensive measurements on their transport properties. A remarkable difference in the behavior and a large anisotropy between in-plane and out-of-plane resistivity was observed. Disorder could explain the in-plane square-root temperature dependence resistivity, and interlayer incoherent scattering may contribute to the out-of-plane transport property. Along the ab plane, the estimated value of the coherence length is 15.5 Å. From measurements of the upper critical magnetic field Hc2 (T ≥ 20 K), we estimate Hc2(0) = 313 T. Thermal conductivity for Ca10(Pt4As8)((Fe0.86Pt0.14)2As2)5 is relatively small, which can be accounted for by the disorder in the crystal and the low-charge carrier density as verified by the Hall effect.

Physical properties of superconducting Ca10(Pt4As8)((Fe0.92Pt0.08)2As2)5 crystal and comprehensive cognition on the transition temperature for Ca10-3(4)-8

“…The value of γ at room temperature 300K is slightly bigger than 4, with the temperature decreasing, γ increases gradually, reaching to ∼9 around T c , which is larger than that of LaO 1−x F x FeAs [22], the most anisotropic system among traditional Fe based superconductors. The value is also larger than that of the work γ∼8 at T c ∼34 K with x=0.14 [10]. It appears that for Ca10-4-8, the smaller Pt doping level x, the lower T c and a much more anisotropic system acquires.…”

“…To comprehend the transport properties in Ca10-3-8 and Ca10-4-8 systems, it is necessary to understand: 1, the electronic properties of both the Pt n−δ As 8 and Fe 1−x Pt x As layers, 2, the relationship between T c and variables n, x and δ. In figure 12(a), we plot T c versus total Pt concentration (n-δ+10x) of Ca 10 (Pt n−δ As 8 )((Fe 1−x Pt x ) 2 As 2 ) 5 available in the literature [1][2][3][7][8][9][10][11][12].…”

“…The measured composition is Ca 10 Pt 4.8 Fe 9.2 As 18 , implying a formula of Ca 10 (Pt 4 As 8 )((Fe 0.92 Pt 0.08 ) 2 As 2 ) 5 for the sample, if platinum selfdoping effect is considered. Compared with the work of x=0.14 [10], besides that the content of Pt in the original mixture was reduced, the cooling time is also shortened, which is not advantageous to the interlayer diffusion of Pt, and this may be other reason for the decrease of the Pt doping level x in the FeAs layer.…”

“…The discovery of superconductivity in Ca 10 (Pt 3 As 8 )(Fe 2 As 2 ) 5 (Ca10-3-8) and Ca 10 (Pt 4 As 8 )(Fe 2 As 2 ) 5 (Ca10-4-8) has generated great interest in the condensed matter community [1][2][3][4][5][6]. Since the year of 2011, a number of reports appeared and showed that this compound has a wide range of transition temperatures (T c ) [1][2][3][7][8][9][10][11][12]. As in other traditional Fe-based superconductors, Ca 10 (Pt n As 8 )(Fe 2 As 2 ) 5 (n = 3,4) forms layered structure building of FeAs superconducting layers separated by the intermediary layers of Ca-Pt n As 8 -Ca, and such arrangement is shown in figures 1(a) and (b).…”