Y-Substitution effects in the crystal field of the trigonal YxRE1-xNi3Ga9 (RE = Tb, Dy, and Ho)

Multipolar ordering arising from the interplay between crystalline electric field (CEF) effects and magnetic interactions has been gaining more attention in 4f systems. In this work, we explore this possibility in the chiral magnets RENi3Ga9 (RE = Tb, Dy and Ho; x = 0.15 and 0.30) through Y-dilution. We present tem-perature-dependence of the M/H curves, isothermal magnetization and heat-capacity experiments. Single crystalline samples grown by Ga self flux allow us to measure the magnetic properties for different crys-tallographic directions. X-ray diffraction patterns analyzed by Rietveld method indicate that all samples crystallize in a trigonal ErNi3Al9-type structure with space group R32. Our results are consistent with an antiferromagnetic order with transition temperatures TN < 20 K for all the studied samples, which decrease gradually with Y-substitution. By using a mean field model including anisotropic near-and next-near-neighbors magnetic interactions and the trigonal CEF Hamiltonian, we are able to study in detail the evolution of the crystal-field scheme and magnetic couplings for these compounds. We show that the spatial charge distribution between the compounds are in agreement, increasing the confidence of the obtained CEF schemes. Finally, we compare our fittings with disorder simulations assuming that CEF effects should not evolve as a function of Y-substitution. Our results show that only disorder effects do not fully describe the experimental data, which may indicate that quadrupolar degrees of freedom indeed have a role in the magnetic properties of this family.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this study, the possibility of multipolar ordering in chiral magnets RENi3Ga9 (RE = Tb, Dy and Ho; x = 0.15 and 0.30) is explored through Y-dilution. Experimental results show that all samples crystallize in a trigonal ErNi3Al9-type structure, and the transition temperatures TN are all below 20 K, decreasing gradually with Y-substitution.