Magnetic and Crystalline Electric Field Effect in Lu_1-xDy_xNi₂B₂C System

To investigate the interplay between magnetism and superconductivity, we have analyzed the magnetic isotherms curves of dilute magnetic systen such as Lu_1-xDy_xNi₂B₂C (x = 0 ~ 1.0) single crystals at high applied magnetic fields parallel and perpendicular to the crystallography c-axis and various low temperature. All above isostructural compounds show some magnetic transitions in magnetization isotherms at certain applied magnetic fields and temperatures above and below Neel and superconducting temperatures (T_N, T_C) where T_N/T_C varies systemetically. Comparing our results by using theoretical group analysis to the energy scheme of crystalline electric field of magnetization anisotropy at various temperatures, we have obtained some temperary low energy levels such as singlet Γ₄ and some excited Γ₅ and Γ_1. Our energy scheme analysis shows qualitative agreement between theoretical caculation and experiments only at high magnetic fields, but disagreement for x > 0.7 regime.