Magnetic properties of R2O2CO3 (R = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb) with a rare earth-bilayer of triangular lattice

Polycrystalline samples of R2O2CO3 (R = Pr, Nd, Gd, Tb, Dy, Ho, Er, and Yb) with a unique rare-earth bilayer of triangular lattice were synthesized and studied by DC and AC magnetic susceptibility. Data reveals various magnetic ground states including (i) a nonmagnetic ground state for the Pr sample; (ii) long-range magnetic ordering for the Nd, Gd, Tb, Dy, Ho, and Er samples. Besides the Gd sample, they also exhibit field-induced spin state transitions. More interestingly, a series of spin state transitions in the Nd and Dy samples could be attributed to the field-induced up-up-down spin state and the 2:1 canted spin state. Neutron powder diffraction measurements of the Er sample suggest a spiral spin structure below its TN; and (iii) a short-range ordering for the Yb sample. The disrupted interlayer interaction due to the shift of Yb3+ ions within the bilayer prevents long-range magnetic ordering down to 30 mK and makes it another Yb-related triangular lattice antiferromagnet that has the potential to realize a quantum spin liquid state.