Magnetic flux structures in RNi2B2C single crystals in normal and superconducting states

RNi2B2C single crystals, where R = Lu, Y, Er, Ho and Tb have been studied by high-resolution Bitter decoration technique, over the wide range temperatures and magnetic fields up to 2 T. Diverse vortex lattice structures were investigated: transition from triangular to square lattice for LuNi2B2C single crystals; peculiar vortex structures associated with antiferromagnetic (AFM) and weak-ferromagnetic (WFM) states below Tc for ErNi2B2C single crystals . In addition, Bitter decoration revealed structures associated with a long range magnetic order in the non-superconducting TbNi2B2C as well as ErNi2B2C in the normal but magnetically ordered state.