Uniaxially anisotropic antiferromagnets in a field along the easy axis
Uniaxially anisotropic antiferromagnets in a field along the easy axis are studied with the help of ground state considerations and Monte Carlo simulations. For classical models, the XXZ model as well as variants, we analyze the role of non-collinear spin configurations of biconical or bidirectional type interpolating between the well-known antiferromagnetic and spin-flop structures. Possible experimental applications to layered cuprate antiferromagnets are discussed. Finally, results of quantum Monte Carlo simulations for the S=1/2 XXZ model on a square lattice are presented, and compared with previous findings.
Evidence for a bicritical point in the XXZ Heisenberg antiferromagnet on a simple cubic lattice.
The classical Heisenberg antiferromagnet with uniaxial exchange anisotropy (XXZ model) in a field on a simple cubic lattice is studied with the help of extensive Monte Carlo simulations. We analyze, in particular, various staggered susceptibilities and Binder cumulants and present clear evidence for the triple point of the antiferromagnetic, spin-flop, and paramagnetic phases being a bicritical point with Heisenberg symmetry. Results are compared to previous predictions applying various theoretical approaches.
ANISOTROPIC SPIN-GLASS BEHAVIOR IN LA1.96SR0.04CUO4
Recent experiments on the spin-glass order parameter of La{sub 1.96}Sr{sub 0.04}CuO{sub 4} are shown to be consistent with a scaling theory which takes into account spin anisotropy. The crossover exponent associated with the anisotropy is found to be 1.0{plus_minus}0.2. {copyright} {ital 1997} {ital The American Physical Society}