Magnetic-Field-Induced Localization of Quasiparticles in Underdoped La$_{2-x}$Sr$_x$CuO$_4$ Single Crystals

TL;DR

This study investigates how magnetic fields influence quasiparticle behavior in underdoped La$_{2-x}$Sr$_x$CuO$_4$ crystals, revealing a magnetic-field-induced localization that may explain the insulating state under high fields.

Contribution

It provides experimental evidence of magnetic-field-induced quasiparticle localization in underdoped cuprates, highlighting a doping-dependent transition in thermal conductivity behavior.

Findings

Quasiparticle localization occurs in underdoped samples under magnetic fields.

Thermal conductivity behavior changes drastically across optimal doping.

Localization may explain the insulating normal state at high magnetic fields.

Abstract

Magnetic-field-induced ordering of electrons around vortices is a striking phenomenon recently found in high-$T_c$ cuprates. To identify its consequence in the quasiparticle dynamics, the magnetic-field ($H$) dependence of the low-temperature thermal conductivity $\kappa$ of La$_{2-x}$Sr$_x$CuO$_4$ crystals is studied for a wide doping range. It is found that the behavior of $\kappa(H)$ in the sub-Kelvin region changes drastically across optimum doping, and the data for underdoped samples are indicative of unusual magnetic-field-induced localization of quasiparticles; this localization phenomenon is probably responsible for the unusual "insulating normal state" under high magnetic fields.