One-magnon Raman scattering in La(2)CuO(4): the origin of the field-induced mode

TL;DR

This study explores one-magnon Raman scattering in La(2)CuO(4), revealing two distinct magnon modes and a field-induced mode indicating a new magnetic state above the Neel temperature.

Contribution

It demonstrates the origin of the field-induced mode in La(2)CuO(4) and links it to a novel magnetic state with in-plane weak-ferromagnetic moments.

Findings

Identified two one-magnon peaks in Raman spectra: DM mode (B1g) and XY mode (B3g).

Observed a field-induced XY mode in planar geometry under magnetic field.

Discovered a new magnetic state above T_N with in-plane WFM orientation.

Abstract

We investigate the one-magnon Raman scattering in the layered antiferromagnetic La(2)CuO(4) compound. We find that the Raman signal is composed by two one-magnon peaks: one in the B1g channel, corresponding to the Dzyaloshinskii-Moryia (DM) mode, and another in the B3g channel, corresponding to the XY mode. Furthermore, we show that a peak corresponding to the XY mode can be induced in the planar (RR) geometry when a magnetic field is applied along the easy axis for the sublattice magnetization. The appearance of such field-induced mode (FIM) signals the existence of a new magnetic state above the Neel temperature T_N, where the direction of the weak-ferromagnetic moment (WFM) lies within the CuO(2) planes.