Magnetic neutron scattering provides evidence for nucleation of antiferromagnetic droplets around impurities in a doped nickel oxide-based quantum magnet. The undoped parent compound contains a spin liquid with a cooperative singlet ground state and a gap in the magnetic excitation spectrum. Calcium doping creates excitations below the gap with an incommensurate structure factor. We show that weakly interacting antiferromagnetic droplets with a central phase shift of π and a size controlled by the correlation length of the quantum liquid can account for the data. The experiment provides a quantitative impression of the magnetic polarization cloud associated with holes in a doped transition metal oxide.
Publication Source (Journal or Book title)
Xu, G., Aeppli, G., Bisher, M., Broholm, C., DiTusa, J., Frost, C., Ito, T., Oka, K., Paul, R., Takagi, H., & Treacy, M. (2000). Holes in a quantum spin liquid. Science, 289 (5478), 419-422. https://doi.org/10.1126/science.289.5478.419