Quantized spin waves in the metallic state of magnetoresistive manganites

TL;DR

This study investigates quantized spin waves in ferromagnetic manganites, revealing energy level structures near the zone boundary that are consistent with a model of 2D clusters embedded in a 3D matrix, across different compositions.

Contribution

It introduces a model of quantized spin waves within 2D clusters to explain anomalies in the metallic state of manganites, supported by high-resolution measurements.

Findings

Spin wave spectra show multiple energy levels near the zone boundary.

Energy levels are consistent across different compositions and states.

A 2D cluster model explains the observed spin wave anomalies.

Abstract

High resolution spin waves measurements have been carried out in ferromagnetic (F) La(1-x)(Sr,Ca)xMnO3 with x(Sr)=0.15, 0.175, 0.2, 0.3 and x(Ca)=0.3. In all q-directions, close to the zone boundary, the spin wave spectra consist of several energy levels, with the same values in the metallic and the x\approx 1/8 ranges. Mainly the intensity varies, jumping from the lower energy levels determined in the x\approx 1/8 range to the higher energy ones observed in the metallic state. On the basis of a quantitative agreement found for x(Sr)=0.15 in a model of ordered 2D clusters, the spin wave anomalies of the metallic state can be interpreted in terms of quantized spin waves within the same 2D clusters, embedded in a 3D matrix.