Neutron-scattering study of spin correlations in La1.94-xSrxCe0.06CuO4

TL;DR

This neutron-scattering study investigates how reduced lattice distortion in La1.94-xSrxCe0.06CuO4 affects low-energy spin correlations, revealing a gap in spin excitations and low-energy components linked to magnetic stability.

Contribution

It provides new insights into the relationship between lattice distortion and spin fluctuations in LSCCO, highlighting differences from LSCO.

Findings

A 6-7 meV gap in spin excitation spectrum for x=0.18 and 0.24 samples.

Observation of a low-energy component below 2-3 meV in x=0.14 sample.

Correlation between low-energy spin fluctuations and CuO2 plane distortion.

Abstract

We performed a neutron-scattering experiment to investigate the effect of distortion of CuO2 planes on the low-energy spin correlation of La1.94-xSrxCe0.06CuO4 (LSCCO). Due to the carrier-compensation effect by co-doping of Sr and Ce, LSCCO has a smaller orthorhombic lattice distortion compared to La2-xSrxCuO4 (LSCO) with comparable hole concentration p. A clear gap with the edge-energy of 6~7 meV was observed in the energy spectrum of local dynamical susceptibility c"(w) for both x=0.18 (p~0.14) and x=0.24 (p~0.20) samples as observed for optimally-doped LSCO (x=0.15~0.18). For the x=0.14 (p~0.10) sample, in addition to the gap-like structure in c"(w) we observed a low-energy component within the gap which develops below 2~3meV with decreasing the energy. The low-energy component possibly coincides with the static magnetic correlation observed in this sample. These results are discussed from a view point of relationship between the stability of low-energy spin fluctuations and the distortion of CuO2 planes.