Absence of dissipationless transport in clean 2D superconductors

TL;DR

This study investigates the absence of dissipationless transport in ultra-thin 2D superconductors, revealing how thickness influences the phase diagram and demonstrating control over dissipative states via non-local transport and simulations.

Contribution

It provides the first detailed dissipation phase diagrams for 2D superconductors down to a monolayer, showing the disappearance of dissipationless transport at minimal thickness and demonstrating control over non-equilibrium states.

Findings

Dissipationless transport exists in four-layer samples but diminishes with fewer layers.

In monolayers, dissipationless transport shrinks to a point at T=B=I=0.

TDGL simulations qualitatively match experimental phase diagrams.

Abstract

Dissipationless charge transport is one of the defining properties of superconductors (SC). The interplay between dimensionality and disorder in determining the onset of dissipation in SCs remains an open theoretical and experimental problem. In this work, we present measurements of the dissipation phase diagrams of SCs in the two dimensional (2D) limit, layer by layer, down to a monolayer in the presence of temperature (T), magnetic field (B), and current (I) in 2H-NbSe2. Our results show that the phase-diagram strongly depends on the SC thickness even in the 2D limit. At four layers we can define a finite region in the I-B phase diagram where dissipationless transport exists at T=0. At even smaller thicknesses, this region shrinks in area. In a monolayer, we find that the region of dissipationless transport shrinks towards a single point, defined by T=B=I=0. In applied field, we show that time-dependent-Ginzburg-Landau (TDGL) simulations that describe dissipation by vortex motion, qualitatively reproduce our experimental I-B phase diagram. Last, we show that by using non-local transport and TDGL calculations that we can engineer charge flow and create phase boundaries between dissipative and dissipationless transport regions in a single sample, demonstrating control over non-equilibrium states of matter.