Field-induced magnetic order in the singlet-ground-state magnet CsFeCl3

The field-induced magnetic order in the singlet-ground-state system CsFeCl{sub 3} (H parallel c) has been studied by the measurements of the magnetization M{sub parallel} (the ferromagnetic component along the c axis) and the magnetic neutron scattering from M{sub perpendicular} (the antiferromagnetic component in the c plane). The field dependence of M{sub perpendicular} has clearly shown that the field-induced ordered phase is described by the order parameter (M{sub perpendicular}=g{sub perpendicular{mu}}{sub B} ). The development of the spin correlation and the incommensurate-commensurate phase transition have been observed in the field region of 5 T H{sub c}). Two possible magnetic configurations have been suggested for the commensurate three dimensional long-ranged order phase. The frustration and the magnetostriction effects have been discussed.