Contrasting magnetic behavior of fine particles of some Kondo Lattices

TL;DR

This study examines how reducing particle size affects the magnetic properties of Kondo lattice compounds, revealing suppression or slight enhancement of magnetic ordering temperatures due to increased 4f-localization.

Contribution

It provides new insights into the size-dependent magnetic behavior of Kondo lattices, highlighting the role of 4f-electron localization in magnetic interactions.

Findings

Magnetic ordering features are suppressed below 1.8 K in fine particles of CeAu2Si2 and CePd2Si2.

CeAl2 shows a marginal increase in TN when particle size is reduced.

Ce valence state remains trivalent despite size reduction.

Abstract

We have investigated the magnetic behavior of ball-milled fine particles of well-known Kondo lattices, CeAu2Si2, CePd2Si2 and CeAl2, by magnetization and heat-capacity studies in order to understand the magnetic behavior when the particle size is reduced. These compounds have been known to order antiferromagnetically in the bulk form near (TN=) 10, 10 and 3.8 K respectively. We find that the features due to magnetic ordering get suppressed to temperatures below 1.8 K in the case of fine particles of ternary alloys, though trivalence of Ce as inferred from the effective moment remains unchanged. In contrast to this, in CeAl2, there appears to be a marginal enhancement of TN, when the particle size is reduced to less than a micron. These results can be consistently understood by proposing that there is relatively more 4f-localization as the particle size is reduced, resulting in weakening of exchange interaction strength.