Magnetic anisotropy and crystalline electric field effects in RRh₄B₄single crystals

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 αJ of the CEF Hamiltonian. A strong influence of magnetic anisotropy on superconductivity was also observed.