Magnetic phase diagram of α-RuCl₃ in magnetic fields oriented away from the crystallographic ab plane

Determining the highly anisotropic magnetic phase diagram of α-RuCl₃ in magnetic fields oriented away from the ab plane is of interest for two reasons: experimentally, a quantum spin liquid phase has been predicted to appear at high fields that are perpendicular, or nearly perpendicular, to the ab plane and theoretically, an accurate determination of the phase diagram will provide a strong constraint on the magnitude of the off-diagonal exchange interaction, Γ. Towards this end, we have used magnetic-torque, magnetocaloric effect, and ac magnetic susceptibility measurements to map out the phase diagram of α-RuCl₃ in magnetic fields up to 40 T as a function of the angle θ between the magnetic field and the ab plane for angles approaching 90° at low temperature, and at 75°, we have determined the phase diagram as a function of both field strength and temperature. Our work reveals a number of new phases.