# Charge-stripe order, antiferromagnetism, and spin dynamics in the cuprate-analog nickelate La$_4$Ni$_3$O$_8$

## TL;DR

This study uses muon spin rotation to investigate charge-stripe and antiferromagnetic order in La4Ni3O8, revealing an abrupt transition at 105 K with weak Ni moments and complex spin dynamics, contrasting with theoretical models.

## Contribution

First muon spin rotation investigation of La4Ni3O8 revealing detailed magnetic order and spin dynamics, highlighting discrepancies with existing theoretical predictions.

## Key findings

- Charge-stripe and AFM order appear at 105 K
- Ni moments are estimated to be less than 0.5μB
- Critical slowing of Ni spin fluctuations observed above transition

## Abstract

We report a muon spin rotation ($\mu$SR) study of the cuprate-analog nickelate La$_4$Ni$_3$O$_8$, which undergoes a transition at 105 K to a low-temperature phase with charge-stripe and antiferromagnetic (AFM) order on square planar NiO$_2$ layers. Zero-field $\mu$SR shows that this transition is abrupt and that the AFM configuration is commensurate. Comparison of observed muon precession frequencies with Ni dipolar field calculations yields Ni moments $\lesssim 0.5\mu_B$. Dynamic muon spin relaxation above 105 K suggests critical slowing of Ni spin fluctuations, but is inconsistent with corresponding $^{139}$La NMR results. Critical slowing and an abrupt transition are also observed in the planar cuprate AFM La$_2$CuO$_{4+\delta}$, where they are evidence for weakly interplanar-coupled two-dimensional AFM spin fluctuations, but our $\mu$SR data do not agree quantitatively with theoretical predictions for this scenario.

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Source: https://tomesphere.com/paper/1903.11706