A Novel Strongly Spin-Orbit Coupled Quantum Dimer Magnet: Yb2Si2O7

Recently published in Physical Review Letters:

The quantum dimer magnet (QDM) is the canonical example of “quantum magnetism”. We report our single crystal neutron diffraction, specific heat, and ultrasound velocity work on a new QDM in the strongly spin-orbit coupled, distorted honeycomb-lattice material Yb2Si2O7. These measurements reveal a gapped singlet zero field ground state with sharp, dispersive excitations. We find a field-induced magnetically ordered phase reminiscent of a BEC phase, with exceptionally low critical fields of Hc1 ~0.4 T and Hc2 ~1.4 T. These results raise the question of how anisotropy in strongly spin-orbit coupled materials modifies the field induced phases of QDMs.