Table 1 Different cases of phonon thermal conductivity

Crystal (T → 0)

small-q phonons

κ ∝ T³

Boundary scattering

^39,47

Crystal (T ~ T_D)

large-q phonons

κ ∝ T⁻¹

Umklapp scattering

^47,48,49

Glass (T → 0)

"propagons”

κ ∝ T^~2

Rayleigh scattering

^50,51,52

Glass (high T)

"diffusons”

κ ∝ T⁰

Minimum mean free path

^52,53,54

Classical liquid

large-q phonons

κ ∝ T⁰

Minimum mean free path

²⁵

Quantum liquid ³He

q ~ 2k_F phonons

κ ∝ T^1/2

Fermi surface thermal fuzziness

This work