Measurement of the magnetic octupole susceptibility of PrV2Al20

TL;DR

This paper introduces a novel method to detect magnetic octupole susceptibility in materials, revealing octupolar fluctuations in PrV2Al20 through combined magnetic field and strain measurements, advancing understanding of hidden electronic orders.

Contribution

The study develops a new experimental approach to probe magnetic octupole susceptibility using magnetic field and strain, enabling detection of elusive octupolar fluctuations.

Findings

Magnetic octupole susceptibility in PrV2Al20 shows Curie-Weiss behavior.

Magnetic octupole fluctuations are observed above the ordering temperature.

Anisotropic strain combined with magnetic fields can probe hidden electronic orders.

Abstract

In the electromagnetic multipole expansion, magnetic octupoles are the subsequent order of magnetic multipoles allowed in centrosymmetric systems, following the more commonly observed magnetic dipoles. As order parameters in condensed matter systems, magnetic octupoles have been experimentally elusive. In particular, the lack of simple external fields that directly couple to them makes their experimental detection challenging. Here, we demonstrate a methodology for probing the magnetic octupole susceptibility using a product of magnetic field $H_i$ and shear strain $\epsilon_{jk}$ to couple to the octupolar fluctuations, while using an adiabatic elastocaloric effect to probe the response to this composite effective field. We observe a Curie-Weiss behavior in the obtained octupolar susceptibility of \ce{PrV2Al20} up to temperatures approximately forty times the putative octupole ordering temperature. Our results demonstrate the presence of magnetic octupole fluctuations in the particular material system, and more broadly highlight how anisotropic strain can be combined with magnetic fields to formulate a versatile probe to observe otherwise elusive emergent `hidden' electronic orders.