Abstract
Using neutron powder diffraction and Monte Carlo simulations we show that a spin-liquid regime emerges at all compositions in the diamond-lattice antiferromagnets . This spin-liquid regime induced by frustration due to the second-neighbor exchange coupling is gradually superseded by antiferromagnetic collinear long-range order at low temperatures. Upon substitution of by in the octahedral B site the temperature range occupied by the spin-liquid regime narrows and increases. To explain the experimental observations we considered magnetic anisotropy or third-neighbor exchange coupling as degeneracy-breaking perturbations. We conclude that is below the theoretical critical point , and that magnetic anisotropy assists in selecting a collinear long-range ordered ground state, which becomes more stable with increasing due to a higher efficiency of as an interaction path compared to .
- Received 21 January 2010
DOI:https://doi.org/10.1103/PhysRevB.81.064416
©2010 American Physical Society