Measurement of the magnetic octupole susceptibility of PrV2Al20

Abstract

Revealing the presence of magnetic octupole order and associated octupole fluctuations in solids is a highly challenging task due to the lack of simple external fields that can couple to magnetic octupoles. Here, we demonstrate a methodology for probing the magnetic octupole susceptibility of a candidate material, PrV₂Al₂₀, using a product of magnetic field H_i and shear strain ϵ_jk as a composite effective field, while employing an adiabatic elastocaloric effect to probe the response. We observe Curie-Weiss behavior in the obtained octupolar susceptibility down to approximately 3 K. Although octupole order does not appear to be the leading multipolar channel in PrV₂Al₂₀, our results nevertheless reveal the presence of strong magnetic octupole fluctuations and hence demonstrate that octupole order is at least a competing state. More broadly, our results highlight how anisotropic strain can be combined with magnetic fields to probe elusive ‘hidden’ electronic orders.

Magnetic dipoles are the lowest order term in a multipolar expansion. The next allowed in centrosymmetric materials is a magnetic octupole, but this is notoriously difficult to probe experimentally, due to a lack of direct coupling to external fields. Here, Ye et al demonstrate a method to overcome this in PrV₂Al₂₀.”