engleski

NMR study of "pinwheel" kagome Rb2Cu3SnF12

Using (63, 65)Cu nuclear magnetic resonance (NMR) in magnetic fields up to 30 T we study the microscopic properties of the 12-site valence-bond-solid ground state in the "pinwheel" kagome compound Rb2Cu3SnF12. We find that the ground state is characterized by a strong transverse staggered spin polarization whose temperature and field dependence points to a mixing of the singlet and triplet states. This is further corroborated by the field dependence of the gap \Delta (H), which has a level anticrossing with a large minimum gap value of \Delta(0), with no evidence of a phase transition down to 1.5 K. By the exact diagonalization of small clusters, we show that the observed anticrossing is mainly due to staggered tilts of the g-tensors defined by the crystal structure, and reveal symmetry properties of the low-energy excitation spectrum compatible with the absence of level crossing.

kagome; nmr; valence bond solid

nije evidentirano