Magnetic Field Effects in Frustrated Low-Dimensional Magnets
B. Schmidt, M. Siahatgar and P. Thalmeier
Max-Planck-Institut für Chemische Physik fester Stoffe, 01187 Dresden, Germany
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We investigate the frustrated two-dimensional S = 1/2 next nearest neighbor anisotropic Heisenberg antiferromagnet on a square lattice as described by the J1a, b - J2 model. We use spin-wave theory and exact diagonalization for finite tiles including a new method for the finite size scaling procedure. We present results obtained from the extension of our numerical method to finite magnetic fields as well as from spin-wave theory. The induced uniform: and the staggered moment in the antiferromagnetically ordered phases in the presence of a magnetic field are calculated. They deviate strongly from classical behaviour depending on frustration ratio J2/J1a, b and the J1a, b exchange anisotropy. The magnetization becomes strongly nonlinear and is suppressed from the classical value. This is due to enhanced quantum fluctuations already at moderate frustration.
DOI: 10.12693/APhysPolA.121.1089
PACS numbers: 75.10.Jm, 75.30.Cr, 75.30.Ds