Magnetic order in lightly doped La_{2-x}Sr_{x}CuO_{4}

TL;DR

This study investigates magnetic excitations in lightly doped La_{2-x}Sr_{x}CuO_{4}, revealing unconventional spin behaviors and a field-induced magnetic state that persists well above the Néel temperature.

Contribution

It uncovers novel collective spin excitations and characterizes magnetic anisotropy effects in lightly doped cuprates, advancing understanding of magnetic order in these materials.

Findings

Identification of magnetic anisotropy gap due to antisymmetric spin interaction

Observation of unconventional in-plane spin anisotropy behavior

Discovery of a field-induced magnetic state persisting above Néel temperature

Abstract

We study long wavelength magnetic excitations in lightly doped La_{2-x}Sr_{x}CuO_{4} (x < 0.03) detwinned crystals. The lowest energy magnetic anisotropy induced gap can be understood in terms of the antisymmetric spin interaction inside the antiferromagnetic (AF) phase. The second magnetic resonace, analyzed in terms of in-plane spin anisotropy, shows unconventional behavior within the AF state and led to the discovery of collective spin excitations pertaining to a field induced magnetically ordered state. This state persists in a 9 T field to more than 100 K above the N\'{e}el temperature in x = 0.01.