Bose Einstein Condensation ​ in a Spin-Orbit Coupled Quantum Dimer Magnet (QDM)

January 9, 2020
Bose Einstein Condensation ​ in a Spin-Orbit Coupled Quantum Dimer Magnet (QDM)
Field dependence of the magnetic excitation spectrum (T=50 mK). (a) Zero field gapped spectrum; (b) The gap is closed in the BEC phase just above 0.4 Tesla. (c) At fields above 1.4 T the gap reopens, and the intensity is weaker and redistributed.​

Scientific Achievement

It is shown that a small magnetic field induces magnon Bose Einstein condensation (BEC) in the QDM Yb2Si2O7, and a slightly larger field leads to an unusual regime related to the material’s strong spin-orbit coupling (SOC).​

Significance and Impact

This study provides a prototypical illustration of how anisotropy arising from strong SOC can lead to new and unexpected collective phenomena even in relatively simple quantum magnetic systems.

Research Details

  • Neutron scattering was used to map out the field dependent phase diagram and character of the ground state.​
  • Magnetization and ultrasound velocity measurements yield additional information

G. Hester, H.S. Nair, T. Reeder, et al., Phys. Rev. Lett., 123, 027201 (2019)