Fig. 5: High-resolution magnetic excitation spectrum of K2Co(SeO3)2 in the supersolid phase.
From: Wannier states and spin supersolid physics in the triangular antiferromagnet K2Co(SeO3)2
False-color plot of inelastic neutron scattering intensity measured in K2Co(SeO3)2 in zero applied field and T = 0.07 K as a function of energy and wave vector transfers along high-symmetry directions on the AMATERAS spectrometer. The incident neutron energy is Ei = 1.69 meV. The energy resolution is 23 μeV at the elastic line. This is to be compared to the 36 μeV resolution of the experiments described in ref. 33. The data are integrated over ±0.5 r.l.u. in l and ±0.05 r.l.u. in the (h, k, 0) plane perpendicular to the cut, and averaged over equivalent paths shown in Supplementary Fig. 3. No background has been subtracted. Both longitudinal and transverse spin fluctuations contribute to scattering, the intensity being proportional to Szz(q, ω) + S⊥(q, ω). White solid lines are the dispersion curves calculated by linear spin wave theory. Circles are first poles of Szz(q, ω) calculated by QMC. The white hexagon represents the Brillouin zone boundary. Γ, K, and M label high symmetry points in the reciprocal space. Inset: a zoom-in view of the low-energy spectrum near the K point with a different color scale to highlight the gapped pseudo-Goldstone excitation. Labels on the top axis indicate the position of energy cuts shown in Fig. 6.
