Staggered-field effect on the magnetic-field-induced magnetization of the one-dimensional antiferromagnet (formula presented)

Magnetic properties in the charge-ordered phase of (formula presented) have been studied by polarized-neutron diffraction. It is revealed that one-dimensional (1D) chains of magnetic (formula presented) ions are formed by charge ordering below 290 K. The field-induced magnetic moment on the 1D chain under a field parallel to the chain behaves as that of a spin-1/2 1D Heisenberg antiferromagnet with a g factor (formula presented) In the case of a field perpendicular to the chain, we observed a pronounced enhancement below about 10 K. The observed enhancement of the field-induced magnetization is reproduced well by a theory which takes into account the staggered-field effect due to the Dzyaloshinsky-Moriya interaction within the 1D magnetic chain.