(color online) Magnetic phase diagram of α-RuCl₃ obtained from various measurements. (a) PM and AFM represent paramagnet and zigzag order, respectively. The low field region of the phase diagram is constructed using magnetization and specific heat data, and the high field region is using NMR data. The magnetic field is applied in the a–b plane. The contour map indicates the exponent of the temperature dependence of the spin-lattice relaxation rate. The inset illustrates the zigzag order in the low-field state. From Ref. [124]. (b) ZZ and QPM represent zigzag order and quantum paramagnet, respectively. The phase boundary between ZZ2 and PM is the transition temperature obtained from specific heat and neutron diffraction measurements. The thick solid line is a fit with the transverse-field Ising model, and the thin solid line is a power-law fit. The dashed line is a power-law fit to the gap size Δ. From Ref. [126]. (c) Transition temperatures and gap values obtained from specific heat measurements. The solid line is a guide to the eye. Dashed lines are the fits of the gap function. The magnetic entropy is shown in a color scale. From Ref. [125]. (d) Phase diagram obtained from specific heat and NMR measurements along with the field dependence of the spin gap Δ extracted from the nuclear-spin relaxation rate (right axis). From Ref. [134]. (e) False-color representation of the T derivative of the ab-plane thermal conductivity (κ_ab) together with the gap values (solid squares) extracted from the phononic fits. The color scale is in units of W/K²·m. From Ref. [133]. (f) Magnetic transition temperature as a function of field obtained from susceptibility measurements with field applied along the [110] direction. The inset shows the susceptibility data. From Ref. [132].