1998/12/23 by S. Brehmer, H. -J. Mikeska, H.-J. Mikeska +5 · 4 citations
Chemistry · Mathematics · Physics and Astronomy · #Bilinear interpolation #Chemistry #Condensed matter physics #Exchange interaction #Ferromagnetism #Magnetic properties of thin films #Mathematics #Perturbation (astronomy) #Perturbation theory (quantum mechanics) #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Ring (chemistry) #Spectral line #Spectrum (functional analysis) #Spin (aerodynamics) #Theoretical and Computational Physics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.60.329
RevTeX, 17 pages, 6 embedded figures, uses epsfig
arxiv created 1998/12/23 · openalex publication_date 1999/07/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate the influence of biquadratic exchange interactions on the low-lying excitations of a S=(1)/(2) ladder using perturbation theory, numerical diagonalization of finite systems, and exact results for ladders with matrix product ground states. We consider in particular the combination of biquadratic exchange interactions corresponding to ring exchange on the basic ladder plaquette. We find that a moderate amount of ring exchange reduces the spin gap substantially and makes equal bilinear exchange on legs and rungs consistent with experimentally observed spectra.