Evidence for the Alternating Next-Nearest Neighbor model in the dynamic behavior of a frustrated antiferromagnet

TL;DR

This study uses X-ray photon correlation spectroscopy to investigate the magnetic dynamics of Lu2CoMnO6, providing evidence supporting the Alternating Next-Nearest Neighbor model in a frustrated antiferromagnet.

Contribution

It demonstrates the application of XPCS to probe magnetic dynamics in a frustrated antiferromagnet and supports a novel model predicting faster dynamics at lower temperatures.

Findings

Bragg peaks slide towards commensurate order with decreasing temperature

Antiferromagnetic inhomogeneities produce speckle dynamics

Data supports the Alternating Next-Nearest Neighbor model prediction of faster dynamics at lower temperatures

Abstract

X-ray photon correlation spectroscopy (XPCS) enables us to study dynamics of antiferromagnets. Using coherent soft X-ray diffraction, we resonantly probe Mn and Co Bragg peaks in the frustrated magnetic chain compound Lu2CoMnO6 significantly below the Neel temperature. Bragg peaks of incommensurate order slide towards commensurate 'up up down down' order with decreasing temperature. Antiferromagnetic inhomogeneities produce speckle within the Bragg peaks, whose dynamics are probed by XPCS and compared to the classic Axial Next-Nearest Neighbor Interaction model of frustration. The data supports a novel model prediction: with decreasing temperature the dynamics become faster.