Anisotropy in Electronic and Magneto-Transport of 2D Superconductor NbSe2

Abstract

This article reports the successful synthesis of single crystalline two-dimensional thin flakes of NbSe₂. The XRD (X-ray diffraction) pattern of the grown crystal ensured its crystallization in a single phase with a hexagonal structure. The EDAX (energy dispersive X-ray analysis) endorsed the stoichiometry of the as-grown sample. To study the vibrational modes, the Raman spectra were recorded, which exhibited the expected four Raman active modes. The resistance vs temperature measurement showed a well-established superconducting transition (T_c) at 7.3 K. The ZFC (zero-field cooled) and FC (field cooled) magnetization curves, as well as the isothermal M−H (magnetization vs field) measurements, have been performed for both in-plane and out-of-plane H directions. Distinct anisotropy is observed in both magnetization and magneto-transport measurements with field direction, leading to different critical fields (H_c). Out-of-plane magneto-transport data hints towards the existence of a filamentary state. The density functional theory (DFT) has been used to study the band structure of NbSe₂. Although the bulk band structure confirmed metallic behavior, the same of mono-layers of NbSe₂ within the GGA+U framework showed a band gap of 1.17 eV. The article addresses the anisotropy in the electronic and magneto-transport of 2D superconductor NbSe₂.