Low temperature magnetism of KAgF3

TL;DR

This study investigates the low-temperature magnetic phases of KAgF3, revealing an A-type antiferromagnetic order below 29K and suggesting an intermediate phase at higher temperatures, using neutron diffraction, μSR spectroscopy, and DFT calculations.

Contribution

The paper combines experimental and theoretical methods to characterize the magnetic phases of KAgF3, identifying a new intermediate phase and detailing the low-temperature magnetic structure.

Findings

KAgF3 orders as an A-type antiferromagnet below 29K.

Evidence suggests an intermediate magnetic phase between 29K and 66K.

The intermediate phase's nature remains unresolved due to detection limits.

Abstract

KAgF$_3$ is a quasi one-dimensional quantum antiferromagnet hosting a series of intriguing structural and magnetic transitions. Here we use powder neutron diffraction, $\mu$SR spectroscopy, and Density Functional Theory calculations to elucidate the low temperature magnetic phases. Below $T_{N1}=29$K we find that the material orders as an A-type antiferromagnet with an ordered moment of 0.47$\mu_{\rm B}$. Both neutrons and muons provide evidence for an intermediate phase at temperatures $T_{N1}<T<T_{N2}$ with $T_{N2}\approx 66$ K from a previous magnetometry study. However, the evidence is at the limit of detection and its nature remains an open problem.