title: Holes in a Quantum Spin Liquid.
abstract: 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 pi 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.
authors.affiliation: Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA. NEC Research Institute, 4 Independence Way, Princeton, NJ 08540, USA. National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899, USA. Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA. ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK. Electrotechnical Laboratory, Tsukuba 305, Japan. Department of Advanced Materials Science, Graduate School of Frontier Sciences, University of Tokyo Hongo, Tokyo 113-8656, Japan.
authors.initials: G
authors.lastname: Xu
authors.initials: G
authors.lastname: Aeppli
authors.initials: ME
authors.lastname: Bisher
authors.initials: C
authors.lastname: Broholm
authors.initials: JF
authors.lastname: DiTusa
authors.initials: CD
authors.lastname: Frost
authors.initials: T
authors.lastname: Ito
authors.initials: K
authors.lastname: Oka
authors.initials: RL
authors.lastname: Paul
authors.initials: H
authors.lastname: Takagi
authors.initials: MM
authors.lastname: Treacy