STSM of Dominik Volavka (Slovakia) at Catalan Institute of Nanoscience and Nanotechnology (Spain): Misfit layer compounds as heavily doped 2D transition metal dichalcogenides

The purpose of the STSM was to characterize prepared misfit layered compounds   La(1-x)Se1.14 (NbSe2) with different amounts of lanthanum vacancies and lead-doped structures [La(1-x) Pbx Se]1.14 (NbSe2) and [La(1-x) Pbx Se]1.14 (NbSe2)2 to create a complete picture of how the amount of La vacancies and doping with lead affects the electronic properties, charge transfer and Ising superconductivity of prepared compounds.

Our previous study has shown that misfit compounds (LaSe)1.14(NbSe2) and (LaSe)1.14(NbSe2)2, as a result of strong spin orbital coupling and broken inversion symmetry, are Ising superconductors with critical fields well above the Pauli limit, which behave as NbSe2 single layer with a rigid doping of ca. 8 × 1014 cm−2 and 6 × 1014 cm−2, respectively[1], [2]. The charge transfer is smaller than expected from stoichiometry, which is caused by the presence of La vacancies [3], therefore, we decided to prepare superconducting misfit compounds with different amounts of La vacancies and with different lead doping.

[1] P. Samuely et al., “Extreme in-plane upper critical magnetic fields of heavily doped quasi-two-dimensional transition metal dichalcogenides,” Phys Rev B, vol. 104, no. 22, Dec. 2021, doi: 10.1103/PhysRevB.104.224507.

[2] R. T. Leriche et al., “Misfit Layer Compounds: A Platform for Heavily Doped 2D Transition Metal Dichalcogenides,” Adv Funct Mater, vol. 31, no. 6, Feb. 2021, doi: 10.1002/adfm.202007706.

[3] T. Samuely et al., “Protection of Ising spin-orbit coupling in bulk misfit superconductors,“, 2023,