University of California
Discovery of Scalar Chiral Spin Order in Some Compounds
Examination of the magnetic torque measurements in some iridates and in RuCl3, which have been thought to be realizations of the Kitaev model, suggests that they have scalar chiral spin-order of the form
< Si · (Sj × Sk) > .
Given an anisotropy so that two of the three spins in the order parameter lie in the plane, a cusp is expected in the energy when a magnetic field B is applied in a direction approaching the normal to the plane. This leads to a discontinuity in Torque with a magnitude ∝ |B|3 . This prediction has been tested in experiments.
Relation of the connection of scalar chiral order to spin-liquids, to topological effects expected, and to the nature of the ground state and excitations for deviations from a spin per site, will also be discussed.