Angular dependence of resistivity in the superconducting state of NdFeAsO$_{0.82}$F$_{0.18}$ single crystals

TL;DR

This study investigates how resistivity in NdFeAsO$_{0.82}$F$_{0.18}$ single crystals varies with angle in the superconducting state, revealing temperature-dependent anisotropy consistent with multi-band superconductivity.

Contribution

The paper demonstrates the angular scaling of resistivity using anisotropic Ginzburg-Landau theory and determines the temperature dependence of anisotropy in this superconductor.

Findings

Resistivity scales onto a single curve under different magnetic fields.

Anisotropy parameter $$ increases from 5.48 to 6.24 as temperature decreases.

Temperature dependence aligns with multi-band superconductivity models.

Abstract

We report the results of angle dependent resistivity of NdFeAsO$_{0.82}$F$_{0.18}$ single crystals in the superconducting state. By doing the scaling of resistivity within the frame of the anisotropic Ginzburg-Landau theory, it is found that the angle dependent resistivity measured under different magnetic fields at a certain temperature can be collapsed onto one curve. As a scaling parameter, the anisotropy $\Gamma$ can be determined for different temperatures. It is found that $\Gamma(T)$ increases slowly with decreasing temperature, varying from $\Gamma \simeq$ 5.48 at T=50 K to $\Gamma \simeq$ 6.24 at T=44 K. This temperature dependence can be understood within the picture of multi-band superconductivity.