Static and Fluctuating Magnetic Moments in the Ferroelectric Metal LiOsO3

Franziska K K Kirschner,Stephen J Blundell,Tom Lancaster,Youguo Shi,Yanfeng Guo,Andrew T Boothroyd,Franz Lang,Francis L Pratt

doi:10.7566/jpscp.21.011013

Franziska K K Kirschner, Stephen J Blundell + Show 6 more

Open Access

https://doi.org/10.7566/jpscp.21.011013

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Abstract

LiOsO$_3$ is the first example of a new class of material called a ferroelectric metal. We performed zero-field and longitudinal-field $\mu$SR, along with a combination of electronic structure and dipole field calculations, to determine the magnetic ground state of LiOsO$_3$. We find that the sample contains both static Li nuclear moments and dynamic Os electronic moments. Below $\approx 0.7\,$K, the fluctuations of the Os moments slow down, though remain dynamic down to 0.08$\,$K. We expect this could result in a frozen-out, disordered ground state at even lower temperatures.

Highlights

The theoretical model of a ferroelectric metal was first postulated by Anderson and Blount in 1965 [1], despite it being previously thought that the conduction electrons in metals would inhibit the electrostatic forces required to facilitate a ferroelectric instability [2, 3]
We present the results of muon-spin relaxation experiments on a powder sample of LiOsO3, in order to determine its magnetic properties
Preliminary experiments were carried out using the low temperature facility (LTF) and general purpose spectrometer (GPS) at the Swiss Muon

Summary

Introduction

The theoretical model of a ferroelectric metal was first postulated by Anderson and Blount in 1965 [1], despite it being previously thought that the conduction electrons in metals would inhibit the electrostatic forces required to facilitate a ferroelectric instability [2, 3]. The susceptibility shows Curie-Weiss-like behaviour below the structural phase transition suggesting the presence of localised paramagnetic moments, but there is no indication of a magnetic ordering transition. LiOsO3 has a G-type antiferromagnetic (AFM) ground state This prediction can be reconciled with the experimental observations through the introduction of Li defects, which reduce the Os magnetic moment and may be responsible for the destruction of magnetic order. In the case that the ferroelectric transition were to be caused by band hybridization, the AFM state is disfavoured as it would result in an insulating ground state instead of a metallic one [13]. It is reasonable to expect that the dynamics may eventually freeze out completely at even lower temperatures, resulting in a ground state consisting of static, disordered Li nuclear moments and static, disordered Os electronic moments

Experimental details

Muon site candidate

Findings

Conclusions