The nature of 4f electron magnetism in the diluted ferromagnetic Kondo lattice, CeIr2B2

TL;DR

This study investigates the magnetic properties of the Ce_(1-x)La_xIr_2B_2 series, revealing persistent ferromagnetism and Kondo effects without quantum criticality, highlighting the role of indirect exchange interactions in 4f electron magnetism.

Contribution

It provides new insights into 4f electron magnetism in CeIr2B2, demonstrating the persistence of ferromagnetism and Kondo effects across a wide dilution range without quantum critical behavior.

Findings

Ferromagnetic order persists down to 0.8 K even at 90% La substitution.

No evidence of quantum critical point or non-Fermi liquid behavior.

Magnetism is governed by indirect exchange interactions, not direct 4f-4f interactions.

Abstract

We report on the physical properties of the series Ce_(1-x)La_xIr_2B_2 (x D 0-0.9), obtained by means of magnetization, heat capacity and electrical resistivity measurements as a function of temperature (down to 0.7 K for the latter two measurements). The Curie temperature of CeIr2B2 (?5 K) is lowered due to La substitution, as expected. However, no quantum critical point or 'non-Fermi liquid' behavior was observed even in the dilute limit of x D 0:9. Interestingly, ferromagnetic ordering persists even for Ce0:1La0:9Ir2B2, below 0.8 K. Among the Ce systems, CeIr2B2 is one of the compounds in which direct 4f-4f interaction does not appear to play any role in the magnetism, which is controlled by the indirect exchange interaction alone. In this compound, the Kondo effect persists in the ferromagnetic ordered state, as inferred from the entropy data.