Magnetic field-induced one-magnon Raman scattering in the magnon Bose-Einstein condensation phase of TlCuCl3

Abstract

We report the observation of the A g-symmetric one-magnon Raman peak in the magnon Bose-Einstein condensation phase of TlCuCl3. Its Raman shift traces the one-magnon energy at the magnetic point, and its intensity is proportional to the squared transverse magnetization. The appearance of the one-magnon Raman scattering originates from the exchange magnon Raman process and reflects the change of the magnetic-state symmetry. Using the bond-operator representation, we theoretically clarify the Raman selection rules, being consistent with the experimental results.