Formation of metallic magnetic clusters in a Kondo-lattice metal: Evidence from an optical study

TL;DR

This study reveals that in the Kondo-lattice metal Tb2PdSi3, localized magnetic moments and itinerant electrons coexist and interact, forming magnetic clusters that influence optical properties and electronic structure, with implications for correlated metals.

Contribution

It provides experimental and theoretical evidence of magnetic cluster formation and coexistence of localized and itinerant magnetism in a Kondo-lattice metal, highlighting a self-organization process.

Findings

Magnetic clusters form at low temperatures in Tb2PdSi3.

Optical spectral weight shifts indicate pseudogap opening.

Magnetic fluctuations lead to electron self-trapping.

Abstract

Magnetic materials are usually divided into two classes: those with localised magnetic moments, and those with itinerant charge carriers. We present a comprehensive experimental (spectroscopic ellipsomerty) and theoretical study to demonstrate that these two types of magnetism do not only coexist but complement each other in the Kondo-lattice metal, Tb2PdSi3. In this material the itinerant charge carriers interact with large localised magnetic moments of Tb(4f) states, forming complex magnetic lattices at low temperatures, which we associate with self-organisation of magnetic clusters. The formation of magnetic clusters results in low-energy optical spectral weight shifts, which correspond to opening of the pseudogap in the conduction band of the itinerant charge carriers and development of the low- and high-spin intersite electronic transitions. This phenomenon, driven by self-trapping of electrons by magnetic fluctuations, could be common in correlated metals, including besides Kondo-lattice metals, Fe-based and cuprate superconductors.