Tuning of Magnetic Properties of \alpha-RuCl_3 Single Crystal by Cr Doping

We study the influence of Cr doping on magnetic properties of \alpha-RuCl_3 single crystals in detail. With increasing Cr content, the c-axial lattice parameter increases gradually, implying that the Cr doping may weaken the interlayer interactions. The magnetism of Ru_1-xCr_xCl_3 single crystals evolves from a long-range AFM order to a possible spin-glass state with Cr doping. The appearance of a possible spin-glass state can be explained by the introduction of FM interaction by Cr^3+ ions, which competes with the AFM interaction between Ru^3+ ions. Moreover, the larger magnetic moment of Cr^3+ ion with S= 3/2 than Ru^3+ ion with J_\rm eff= 1/2 also results in a monotonic increase of the effective moment of Ru_1-xCr_xCl_3 single crystal.