Magnetic-Field Induced Localization in the Normal State of Superconducting La_2-xSr_xCuo_4

TL;DR

This study investigates how magnetic fields induce a transition from weak to strong localization in the normal state of underdoped La_{2-x}Sr_xCuO_4 superconducting films, revealing a potential zero-field transition to extended electronic states.

Contribution

It demonstrates magnetic-field induced localization transition and introduces a scaling analysis linking conductance to localization length in underdoped cuprate films.

Findings

Magnetic fields cause a transition from weak to strong localization.

Conductance data collapse onto a single scaling curve.

Localization length diverges near zero magnetic field.

Abstract

Magnetoresistance measurements of highly underdoped superconducting La_{2-x}Sr_xCuO_4 films with $x = 0.051$ and $x = 0.048$, performed in dc magnetic fields up to 20 T and at temperatures down to 40 mK, reveal a magnetic-field induced transition from weak to strong localization in the normal state. The normal-state conductances per CuO_2--plane, measured at different fields in a single specimen, are found to collapse to one curve with the use of a single scaling parameter that is inversely proportional to the localization length. The scaling parameter extrapolates to zero near zero field and possibly at a finite field, suggesting that in the zero-field limit the electronic states may be extended.