2001/04/30 by Kwon Park, Subir Sachdev · 3 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.64.184510
published as Physical Review B 64, 184510 (2001) · 16 pages + 14 pages of appendices, 18 figures; (v3) expanded discussion of theory and experimental implications; (v4) Removed some introductory review discussion and moved it to cond-mat/0108238
arxiv created 2001/08/16 · openalex publication_date 2001/10/18 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The ground states and excitations of two-dimensional insulating and doped Mott insulators are described by a bond-operator formalism. While the method represents the degrees of freedom of an arbitrary antiferromagnet exactly, it is especially suited to systems in which there is a natural pairing of sites into bonds, as in states with spontaneous or explicit spin-Peierls order (or bond-centered charge order). In the undoped insulator, as discussed previously, we obtain both paramagnetic and magnetically ordered states. We describe the evolution of superconducting order in the ground state with increasing doping---at low doping, the superconductivity is weak, can coexist with magnetic order, and there are no gapless spin-1/2 fermionic excitations; at high doping, the magnetic order is absent and we obtain a BCS d-wave superconductor with gapless spin-1/2 nodal fermions. We present the critical theory describing the onset of these nodal fermionic excitations. We discuss the evolution of the spin spectrum and obtain regimes where a spin-1 exciton contributes a sharp resonance in the dynamic spin susceptibility. We also discuss the experimental consequences of low-energy, dynamically fluctuating spin-Peierls order in an isotropic CuO2 plane---we compute consequences for the damping and dispersion of an optical phonon involving primarily the O ions and compare the results with recent neutron scattering measurements of phonon spectra.