Direct observation of paramagnons in palladium

TL;DR

This study uses inelastic neutron scattering to observe and analyze paramagnons in palladium, revealing their energy dispersion, damping, and impact on heat capacity, advancing understanding of spin fluctuations in nearly-ferromagnetic metals.

Contribution

First direct observation and detailed analysis of paramagnons in palladium using neutron scattering, providing insights into their dynamics and thermodynamic effects.

Findings

Paramagnons observed up to 128 meV energy

Large relaxation rates lead to minimal heat capacity contribution

Results align with Moriya-Lonzarich spin fluctuation model

Abstract

We report an inelastic neutron scattering study of the spin fluctuations in the nearly-ferromagnetic element palladium. Dispersive over-damped collective magnetic excitations or ``paramagnons'' are observed up to 128 meV. We analyze our results in terms of a Moriya-Lonzarich-type spin fluctuation model and estimate the contribution of the spin fluctuations to the low temperature heat capacity. In spite of the paramagnon excitations being relatively strong, their relaxation rates are large. This leads to a small contribution to the low-temperature electronic specific heat.