Temperature dependence of resistivity and Hall-coefficient in a strongly disordered metal: NbN

TL;DR

This study investigates how resistivity and Hall coefficient vary with temperature in disordered NbN thin films, revealing behaviors inconsistent with current theories of localization and electron-electron interactions.

Contribution

It provides new experimental data on temperature-dependent transport properties in strongly disordered NbN films, challenging existing theoretical models.

Findings

Resistivity and Hall coefficient are negative up to 300K in highly disordered films.

Hall coefficient varies linearly with resistivity across all samples.

Observed behaviors are inconsistent with current localization and interaction theories.

Abstract

We report the temperature dependence of resistivity (rho) and Hall coefficient (R_H) in the normal state of homogeneously disordered epitaxial NbN thin films with kFl~3.27-10.12. The superconducting transition temperature (Tc) of these films varies from 8.13K to 16.8K. While our least disordered film displays usual metallic behavior, for all the films with kFl<8.13, both and are negative up to 300K. We observe that R_H(T) varies linearly with rho(T) for all the films. Measurements performed on a 2nm thick Be film shows similar behavior >. This behavior is inconsistent with existing theories of localization and e-e interactions in a disordered metal.