In-plane and transverse superconducting fluctuation diamagnetism in the presence of charge-density waves in 2H-NbSe2 single crystals

TL;DR

This study investigates the anisotropic superconducting fluctuation diamagnetism in 2H-NbSe2 single crystals, revealing nonlocal effects and ruling out charge-density wave contributions above the transition temperature.

Contribution

It provides the first detailed measurement of fluctuation diamagnetism in both crystallographic directions of 2H-NbSe2, highlighting anisotropic nonlocal effects and clarifying the role of charge-density waves.

Findings

Superconducting fluctuation diamagnetism is highly anisotropic.

Nonlocal electrodynamic effects significantly influence FD.

Charge-density waves do not contribute to FD above Tc.

Abstract

The fluctuation-diamagnetism (FD) above the superconducting transition was measured in 2H-NbSe2 single crystals. The moderate uniaxial anisotropy of this compound, and some experimental improvements, allowed to measure the superconducting fluctuation effects in the two main crystallographic directions. These results reveal that the nonlocal electrodynamic effects on the FD are highly anisotropic, and they also discard a possible contribution to the FD coming from the charge-density waves (CDW) appearing below $Tcdw > Tc in 2H-NbSe2, in agreement with a phenomenological estimate.