Measurement of the magnetic octupole susceptibility of PrV2Al20
Linda Ye, Matthew E. Sorensen, Maja D. Bachmann, I. R. Fisher
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 Hi and shear strain ϵjk 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.”