Strong enhancement of spin fluctuations in the low-temperature-tetragonal phase of antiferromagnetically ordered La_{2-x-y}Eu_ySr_xCuO_4

TL;DR

This study reveals a significant increase in spin fluctuations in the low-temperature tetragonal phase of lightly hole-doped La_{2-x-y}Eu_ySr_xCuO_4, linked to weakened interlayer exchange and hole dynamics, without evidence of stripe phases.

Contribution

It demonstrates the enhancement of spin fluctuations in the tetragonal phase and clarifies the magnetic decoupling and effects of hole motion in this compound.

Findings

Strong magnetic fluctuations detected in the tetragonal phase.

Magnetic decoupling of CuO_2 planes in this phase.

No evidence of stripe phase formation at low doping.

Abstract

Measurements of the static magnetization, susceptibility and ESR of Gd spin probes have been performed to study the properties of antiferromagnetically ordered La_{2-x-y}Eu_ySr_xCuO_4 (x less or equal 0.02) with the low temperature tetragonal structure. According to the static magnetic measurements the CuO_2 planes are magnetically decoupled in this structural phase. The ESR study reveals strong magnetic fluctuations at the ESR frequency which are not present in the orthorhombic phase. It is argued that this drastic enhancement of the spin fluctuations is due to a considerable weakening of the interlayer exchange and a pronounced influence of hole motion on the antiferromagnetic properties of lightly hole doped La_2CuO_4. No evidence for the stripe phase formation at small hole doping is obtained in the present study.