Impurity susceptibility and the fate of spin-flop transitions in lightly-doped La(2)CuO(4)

TL;DR

This study explores how different impurities affect spin-flop transitions in lightly-doped La(2)CuO(4), revealing that impurity type influences the nature of spin reorientation and magnon gap behavior under magnetic fields.

Contribution

It demonstrates how impurity strength and frustration alter spin-flop transition characteristics and magnon gap responses in La(2)CuO(4) and its doped variants.

Findings

Large impurities suppress intermediate spin-flop and cause smooth reorientation.

Small impurities lead to a two-step, discontinuous spin-flop transition.

Magnon gap field dependence differs between doped and undoped samples.

Abstract

We investigate the occurrence of a two-step spin-flop transition and spin reorientation when a longitudinal magnetic field is applied to lightly hole-doped La(2)CuO(4). We find that for large and strongly frustrating impurities, such as Sr in La(2-x)Sr(x)CuO(4), the huge enhancement of the longitudinal susceptibility suppresses the intermediate flop and the reorientation of spins is smooth and continuous. Contrary, for small and weakly frustrating impurities, such as O in La(2)CuO(4+y), a discontinuous spin reorientation (two-step spin-flop transition) takes place. Furthermore, we show that for La(2-x)Sr(x)CuO(4) the field dependence of the magnon gaps differs qualitatively from the La(2)CuO(4) case, a prediction to be verified with Raman spectroscopy or neutron scattering.