Crystal growth, magnetic, and magnetocaloric properties of J_eff = 1/2 quantum antiferromagnet CeCl_3

TL;DR

This study reports the synthesis and comprehensive characterization of CeCl3 crystals, revealing their magnetic anisotropy and magnetocaloric properties, with potential applications in magnetic cooling technologies.

Contribution

First detailed analysis of CeCl3's crystal growth, magnetic, and magnetocaloric properties, highlighting its potential as a high-performance magnetic refrigerant.

Findings

CeCl3 crystals exhibit large magnetic anisotropy.

A significant magnetocaloric effect with entropy change of 23 J/Kg/K near 2.5 K.

No magnetic ordering detected above 2 K, but field-induced effects are prominent.

Abstract

We report growth of high-quality single crystals of CeCl3 using a modified Bridgman Stockbarger method in an infrared image furnace. The grown crystals are characterized using single-crystal/powder X-ray diffraction, Laue X-ray diffraction, Raman spectroscopy, magnetization, and heat capacity probes. CeCl3 crystallizes in a hexagonal structure with a weak trigonal distortion. The Raman spectrum at 300 K showcases five, clearly resolvable, phonon modes at 106.8, 181.2, 189, 213, and 219.7 wavenumbers. The magnetic susceptibility show a large anisotropy with a broad peak in the perpendicular orientation, which is explained using the crystal field theory. The crystal field in CeCl3 splits the J = 5/2 manifold of Ce3+ into three Kramers doublets, resulting in a well-isolated ground state. In the specific heat, no magnetic ordering is detected above 2 K. However, in non-zero fields the low-temperature specific heat changes dramatically, showcasing a peak at 2.5 K under a moderate field of 30 kOe. The weak Ce-Ce exchange, large Ce moment in the crystal field ground state, and significant anisotropy are ingredients for realizing a high magnetocaloric effect. A maximum entropy change of 23 J/Kg/K is observed near 2.5 K in fields ranging from 50 kOe to 60 kOe. These values are comparable to some of the best Gd-based magnetocaloric materials, signifying the potential of CeCl3 as a magnetic coolant.