Crystal structure and anisotropic magnetic properties of new ferromagnetic Kondo lattice compound Ce(Cu,Al,Si)2

TL;DR

This study reports the synthesis, crystal structure, and magnetic properties of a new ferromagnetic Kondo lattice compound CeCu0.18Al0.24Si1.58, revealing its anisotropic magnetic behavior and heavy fermion characteristics.

Contribution

The paper introduces a new Ce-based compound with detailed structural and magnetic analysis, highlighting its ferromagnetic order and Kondo lattice behavior.

Findings

CeCu0.18Al0.24Si1.58 orders ferromagnetically at 9.3 K

The compound exhibits anisotropic magnetization reorientation

It shows heavy fermion behavior with a Sommerfeld coefficient of ~100 mJ/mol K2

Abstract

Single crystals of the new compound CeCu0.18Al0.24Si1.58 have been grown by high-temperature solution growth method using a eutectic Al-Si mixture as flux. This compound is derived from the binary CeSi2 (tetragonal ThSi2-type, Pearson symbol tI12, space group I41/amd) obtained by partial substitution of Si by Cu and Al atoms but showing full occupation of the Si crystal site (8e). While CeSi2 is a well-known valence-fluctuating paramagnetic compound, the CeCu0.18Al0.24Si1.58 phase orders ferromagnetically at TC = 9.3 K. At low temperatures the easy-axis of magnetization is along the a-axis, which re-orients itself along the c-axis above 30 K. The presence of hysteresis in the magnetization curve, negative temperature coefficient of resistivity at high temperatures, reduced jump in the heat capacity and a relatively lower entropy released up to the ordering temperature, and enhanced Sommerfeld coefficient (~100 mJ/mol K2) show that CeCu0.18Al0.24Si1.58 is a Kondo lattice ferromagnetic, moderate heavy fermion compound. Analysis of the high temperature heat capacity data in the paramagnetic region lets us infer that the crystal electric field split doublet levels are located at 178 and 357 K, respectively, and Kondo temperature (8.4 K) is of the order of TC in CeCu0.18Al0.24Si1.58.