The estimation of coherence length for electron-doped superconductor Nd$_{2-x}$Ce$_x$CuO$_{4+\delta}$

TL;DR

This study measures the upper critical field in Nd$_{2-x}$Ce$_x$CuO$_{4+ ext{δ}}$ single crystals to estimate the coherence length and determine the nature of superconductivity, finding it consistent with BCS theory.

Contribution

It provides the first estimation of the coherence length and $k_F \xi$ product for NdCeCuO, confirming its alignment with conventional BCS superconductivity.

Findings

$k_F \xi \,\approx\, 100$ for studied crystals

NdCeCuO exhibits parameters consistent with BCS superconductivity

Coherence length and $k_F \xi$ product are estimated from critical field measurements

Abstract

Results of low-temperature upper critical field measurements for Nd$_{2-x}$Ce$_x$CuO$_{4+\delta}$ single crystals with various $x$ and nonstoichiometric disorder ($\delta$) are presented. The coherence length of pair correlation $\xi$ and the product $k_F$$\xi$, where $k_F$ is the Fermi wave vector, are estimated. It is shown that for investigated single crystals parameter $k_F$$\xi$ $\cong$ 100 and thus phenomenologically NdCeCuO - system is in a range of Cooper-pair-based (BCS) superconductivity.