Singlet Ground State of the Quantum Antiferromagnet Ba3CuSb2O9
arXiv:1207.6469 · doi:10.1103/PhysRevLett.109.117203
Abstract
We present local probe results on the honeycomb lattice antiferromagnet Ba3CuSb2O9. Muon spin relaxation measurements in zero field down to 20 mK show unequivocally that there is a total absence of spin freezing in the ground state. Sb NMR measurements allow us to track the intrinsic susceptibility of the lattice, which shows a maximum at around 55 K and drops to zero in the low-temperature limit. The spin-lattice relaxation rate shows two characteristic energy scales, including a field-dependent crossover to exponential low-temperature behavior, implying gapped magnetic excitations.
Accepted for publication in Physical Review Letters