Phase Diagram of α-RuCl₃ in an in-plane Magnetic Field

The layered honeycomb material α-RuCl₃ is thought to be a material with significant Kitaev magnetic interactions, an unusual bond-dependent Hamiltonian that can support a spin liquid ground state. Although α-RuCl₃ orders magnetically and is thus not a realization of the Kitaev spin liquid, there have been some indications that the material is in some sense close to the spin liquid phase. Remarkably, it has been found that the application of an external magnetic field destabilizes the zigzag magnetic order in this material. We will present magnetic neutron diffraction measurements of the magnetic order parameter, showing the disappearance of the zigzag magnetic order. These measurements are combined with bulk magnetization and heat capacity measurements to map out the low temperature phase diagram in the presence of an in-plane magnetic field, and characterize the different phases observed.