Physical review. B, Condensed matter
Bulk and surface spin-flop transitions in an antiferromagnetic XYZ chain
J. Karadamoglou, N. Papanicolaou
Abstract
Spin-flop transitions are studied within a spin-$\frac{1}{2}$ antiferromagnetic XYZ chain immersed in a uniform bias magnetic field. For a special choice of anisotropy the bulk spin-flop transition occurs at a critical field ${H}_{b}$ characterized by the onset of ``accidental'' degeneracy in the energy spectrum that may indicate a hidden symmetry. On an open chain the bulk transition is preceded by a surface spin-flop transition induced by a surface magnon that turns soft at a new critical field ${H}_{s}<{H}_{b},$ while an antiferromagnetic domain wall is realized in the ground state as the bias field approaches ${H}_{b}.$ These $T=0$ phase transitions could be observed through electron-spin resonance on magnetic chains doped with nonmagnetic ions.