Anisotropic superconductivity and Fermi surface reconstruction in the spin-vortex antiferromagnetic superconductor CaK(Fe$_{0.95}$Ni$_{0.05}$)$_4$As$_4$

José Benito Llorens; Edwin Herrera; Víctor Barrena; Beilun Wu; Niclas Heinsdorf; Vladislav Borisov; Roser Valentí; William R. Meier; Sergey Bud'ko; Paul C. Canfield; Isabel Guillamón; Hermann Suderow

doi:10.1103/physrevb.103.l060506

arXiv · 2009.11246

Anisotropic superconductivity and Fermi surface reconstruction in the spin-vortex antiferromagnetic superconductor CaK(Fe$_{0.95}$Ni$_{0.05}$)$_4$As$_4$

José Benito Llorens·Edwin Herrera·Víctor Barrena·Beilun Wu·Niclas Heinsdorf·Vladislav Borisov·Roser Valentí·William R. Meier·Sergey Bud'ko·Paul C. Canfield·Isabel Guillamón·Hermann Suderow

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Abstract

High critical temperature superconductivity often occurs in systems where an antiferromagnetic order is brought near $T=0K$ by slightly modifying pressure or doping. CaKFe$_4$As$_4$ is a superconducting, stoichiometric iron pnictide compound showing optimal superconducting critical temperature with $T_c$ as large as $38$ K. Doping with Ni induces a decrease in $T_c$ and the onset of spin-vortex antiferromagnetic order, which consists of spins pointing inwards to or outwards from alternating As sites on the diagonals of the in-plane square Fe lattice. Here we study the band structure of CaK(Fe$_{0.95}$Ni$_{0.05}$)$_4$As$_4$ (T$_c$ = 10 K, T$_N$ = 50 K) using quasiparticle interference with a Scanning Tunneling Microscope (STM) and show that the spin-vortex order induces a Fermi surface reconstruction and a fourfold superconducting gap anisotropy.

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José Benito Llorens, Edwin Herrera, Víctor Barrena, Beilun Wu, Niclas Heinsdorf, Vladislav Borisov, Roser Valentí, William R. Meier, Sergey Bud'ko, Paul C. Canfield, Isabel Guillamón, Hermann Suderow. 2020-09-23. Anisotropic superconductivity and Fermi surface reconstruction in the spin-vortex antiferromagnetic superconductor CaK(Fe$_{0.95}$Ni$_{0.05}$)$_4$As$_4$. https://doi.org/10.1103/physrevb.103.l060506

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