Novel Strongly Spin-Orbit Coupled Quantum Dimer Magnet: Yb_{2}Si_{2}O_{7}.

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Materials Science

Background:

• Quantum dimer magnets (QDMs) are key to understanding quantum magnetism.
• They often display field-induced triplon Bose-Einstein condensate (BEC) phases.

Purpose of the Study:

• To investigate a new QDM in the Yb_{2}Si_{2}O_{7} material.
• To characterize its field-induced phases and understand the role of anisotropy.

Main Methods:

• Single crystal neutron scattering
• Specific heat measurements
• Ultrasound velocity measurements
• Inelastic neutron scattering in applied magnetic fields

Main Results:

• A gapped singlet ground state with sharp excitations was observed at zero field.
• A field-induced magnetically ordered phase, resembling a triplon BEC, was found at low critical fields (H_{c1}∼0.4 T, H_{c2}∼1.4 T).
• A gapless Goldstone mode persisted throughout the ordered phase.
• An unusual regime emerged at high fields (≥1.2 T), indicated by changes in ultrasound velocity, magnetization, and specific heat anomalies.

Conclusions:

• Yb_{2}Si_{2}O_{7} hosts a QDM with a field-induced triplon BEC-like phase.
• Anisotropy in this strongly spin-orbit coupled material appears to modify the expected BEC phase at high fields.
• Further research is needed to understand how anisotropy affects field-induced phases in such materials.