  Zel'dovich (spin) anapole correlations in Sr2IrO4 unveiled by magnetic
neutron diffraction contravene the spin-orbit coupled ground state used by the
jeff = 1/2 (pseudo-spin) model. Specifically, spin and space know inextricable
knots which bind each to the other in the iridate. The diffraction property
studied in the Letter is enforced by strict requirements from quantum mechanics
and magnetic symmetry. It has not been exploited in the past, whereas neutron
diffraction by anapole moments is established. Entanglement of the electronic
degrees of freedom is captured by binary correlations of the anapole and
position operators, and hallmarked in the diffraction amplitude by axial atomic
multipoles with an even rank.
