Protection of Ising spin-orbit coupling in bulk misfit superconductors

Tomas Samuely; Darshana Wickramaratne; Martin Gmitra; Thomas Jaouen; Ondrej Šofranko; Dominik Volavka; Marek Kuzmiak; Jozef Haniš; Pavol Szabó; Claude Monney; Geoffroy Kremer; Patrick Le Fèvre; François Bertran; Tristan Cren; Shunsuke Sasaki; Laurent Cario; Matteo Calandra; Igor I. Mazin; Peter Samuely

doi:10.1103/PhysRevB.108.L220501

Protection of Ising spin-orbit coupling in bulk misfit superconductors

Tomas Samuely, Darshana Wickramaratne, Martin Gmitra, Thomas Jaouen, Ondrej Šofranko, Dominik Volavka, Marek Kuzmiak, Jozef Haniš, Pavol Szabó, Claude Monney, Geoffroy Kremer, Patrick Le Fèvre, François Bertran, Tristan Cren, Shunsuke Sasaki, Laurent Cario, Matteo Calandra, Igor I. Mazin, Peter Samuely

DOI 10.1103/PhysRevB.108.L220501 · Physical Review B

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Abstract

Ising superconductivity is present due to the combined effect of broken-inversion symmetry and spin-orbit coupling that locks the spins out of plane, features that are associated with two-dimensional materials. We show that bulk misfit superconductors, (LaSe)1.14(NbSe2) and (LaSe)1.14(NbSe2)2, comprising monolayers and bilayers of NbSe2, exhibit unexpectedly strong Ising protection with a Pauli-limit violation comparable to monolayer NbSe2. We establish these misfit compounds as Ising superconductors using complementary experimental methods in combination with first-principles calculations. A concerted effect of charge-transfer, defects, reduction of interlayer hopping, and stacking enables Ising superconductivity in these compounds and therefore provides a possible pathway to design of bulk superconductors that are resilient to magnetic fields.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
(LaSe)1.14(NbSe2) Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.23	Pressure not reported	unknown
(LaSe)1.14(NbSe2)2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5.7	Pressure not reported	unknown