Emergence of superconductivity in single-crystalline LaFeAsO under simultaneous Sm and P substitution

We report on the high-pressure growth, structural characterization, and investigation of the electronic properties of single-crystalline LaFeAsO co-substituted by Sm and P, in both its normal-and super-conducting states. Here, the appearance of superconductivity is attributed to the inner chemical pressure induced by the smaller-size isovalent substituents. X-ray structural refinements show that the partial substitution of La by Sm and As by P in the parent LaFeAsO compound leads to a contraction in both the conducting Fe-2(As,P)(2) layers and the interlayer spacing. The main parameters of the superconducting state, including the critical temperature, the lower-and upper critical fields, as well as the coherence length, the penetration depth, and their anisotropy, were determined from magnetometry measurements on a single -crystalline La0.87Sm0.13FeAs0.91P0.09O sample. The critical current density (jc), as resulting from loops of magnetization hysteresis in the self-generated magnetic field, is 2 x 10(6) A/cm(2) at 2 K. Overall, our findings illustrate a rare and interesting case of how superconductivity can be induced by co-substitution in the 1111 family. Such approach delineates new possibilities in the creation of superconductors by design, thus sti-mulating the exploration of related systems under multi-chemical pressure conditions. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

Automated summary

We present a study on the electronic properties of LaFeAsO single crystals co-substituted with Sm and P, both in normal and superconducting states. The appearance of superconductivity is believed to be caused by the inner chemical pressure induced by the smaller-size isovalent substituents. The results demonstrate the potential of co-substitution as a method to induce superconductivity in the 1111 family, opening up new possibilities for the design and creation of superconductors through chemical manipulation.