(color online) (a) Low-temperature plot of κ_xx/T as a function of T² of dmit-131 (circles), dmit-221 (diamonds), and κ-(ET)₂Cu₂(CN)₃ (squares). The inset shows κ/T plotted as a function of T. (b) Field dependence of κ normalized by the zero-field value, [κ_xx(H) − κ_xx(0)]/κ_xx(0) of dmit-131 at low temperatures. Upper left inset shows a schematic of the measurement setup. The lower left inset shows thermal-Hall angle tan /( ) as a function of the field value μ₀H at 0.23 K (triangles), 0.70 K (circles), and 1.0 K (diamonds). κ_xy and are the thermal-Hall conductivity and phonon-contributed thermal conductivity, respectively. From Ref. [54].