Anisotropic Ru3+ 4d5 magnetism in the α-RuCl3 honeycomb system: Susceptibility, specific heat, and zero-field NMR.

Hexagonal α-Ru trichloride single crystals exhibit a strong magnetic anisotropy and we show that upon applying fields up to 14 T in the honeycomb plane the successive magnetic order at T1 = 14 K and T2 = 8 K could be completely suppressed whereas in the perpendicular direction the magnetic order is robust. Furthermore the field dependence of Χ(T) implies coexisting ferro- and antiferromagnetic exchange between in-plane components of Ru3+spins, whereas for out-of-plane components a strong antiferromagnetic exchange becomes evident. 101Ru zero-field nuclear magnetic resonance in the ordered state evidence a complex (probably non coplanar chiral) long-range magnetic structure. The large orbital moment on Ru3+ is found in density-functional calculations. [ABSTRACT FROM AUTHOR]