Normal-state resistivity anisotropy in underdoped RBa_2Cu_3O_{6+x} crystals

TL;DR

This study uncovers two mechanisms behind c-axis resistivity in underdoped RBa_2Cu_3O_{6+x} crystals, showing how magnetic order affects electronic transport and superconductivity.

Contribution

It reveals the coexistence of two distinct c-axis transport mechanisms and how antiferromagnetic order influences resistivity anisotropy and superconductivity in underdoped cuprates.

Findings

Identification of a crossover to metal-like behavior at T_m

Antiferromagnetic order blocks the metal-like conduction

Resistivity anisotropy saturates at low temperatures

Abstract

We have revealed new features in the out-of-plane resistivity rho_c of heavily underdoped RBa_2Cu_3O_{6+x} (R=Tm,Lu) single crystals, which give evidence for two distinct mechanisms contributing the c-axis transport. We have observed a crossover towards "metal-like" (d rho_c/d T > 0) behavior at the temperature T_m which quickly increases with decreasing doping. The "metal-like" conductivity contribution dominates at T < T_m and provides a saturation of the resistivity anisotropy, rho_c / rho_{ab}. The antiferromagnetic ordering is found to block this "metal-like" part of the c-axis conductivity and complete decoupling of CuO_2 planes, which may be the reason of superconductivity disappearance.