Figure 1: Liquid helium excitation spectrum S(Q, ) from inelastic neutron scattering measurements. | Nature

Figure 1: Liquid helium excitation spectrum S(Q, ) from inelastic neutron scattering measurements.

From: Quasiparticle breakdown in a quantum spin liquid

Figure 1

Main panel, excitation spectrum in 4He for 1.5 ≤ T ≤ 1.8 K. Data for wavevector Q ≥ 2.3 Å-1 are reproduced from ref. 13, data at smaller Q are from C.L.B. and S.-H. Lee, unpublished results. Solid black line, dispersion from ref. 13; red circle with cross, spectrum termination point at Q = Qc and ω = 2Δ. White line, Feynman–Cohen bare dispersion in absence of decays17; horizontal red line at ω = 2Δ, onset of two-roton states for ω ≥ 2Δ. Inset, excitations near termination point, at Q = 2.6 Å-1Qc, for several temperatures13.

Back to article page