Magnetic anisotropy and crystalline electric field effects in RRh₄B₄ single crystals

Abstract

Research on polycrystalline RRh₄B₄ samples has shown that crystalline electric field (CEF) effects play an important role in these compounds. The successful synthesis of single crystal samples of RRh₄B₄ with R = Y, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Lu has provided an opportunity to further investigate CEF effects in these materials. Magnetization and magnetic susceptibility measurements on the RRh₄B₄ single crystals revealed strong magnetic anisotropy, and the experimental results could be described well by CEF calculations based on the parameters derived from an analysis of experimental data for ErRh₄B₄ single crystals. The easy directions of magnetization of these compounds are consistent with the signs of the Stevens factor α_J of the CEF Hamiltonian. A strong influence of magnetic anisotropy on superconductivity was also observed.

Keywords:

• crystalline electric field
• rare earth compound
• magnetic anisotropy
• superconductivity

Acknowledgements

We thank J.W. Chen for assistance with the electrical resistance measurements. Research at UCSD is supported by the U.S. Department of Energy under Grant No. DE-FG02-04ER46105 (crystal growth) and the National Science Foundation under Grant No. 0802478 (magnetic measurements). Work at Argonne National Laboratory is supported under Contract No. DE-AC02-06CH11357 by U. Chicago Argonne, LLC, Operator of Argonne National Laboratory, a U.S. Department of Energy Office of Science Laboratory.