Absence of magnetic order and emergence of unconventional fluctuations in J_{\rm eff} =1/2 triangular lattice antiferromagnet YbBO_3

We present the ground state properties of a new quantum antiferromagnet YbBO_3 in which the isotropic Yb^{3+} triangular layers are separated by a non-magnetic layer of partially occupied B and O(2) sites. The magnetization and heat capacity data establish a spin-orbit entangled effective spin J_{\rm eff} = 1/2 state of... Show more