Incommensurate nature of the antiferromagnetic order in GdCu

Kaneko, Koji   ; Tabata, Chihiro; Hagihara, Masato   ; Yamauchi, Hiroki   ; Kubota, Masato ; Osakabe, Toyotaka  ; Onuki, Yoshichika*

A magnetic order in orthorhombic GdCu was investigated by a single crystal neutron diffraction with thermal neutron. Magnetic peaks were observed at incommensurate positions described by the ordering vector =(~1~0) with =0.678 at 4~K. This ordering vector is close to the commensurate one with =(2/3~1~0) reported earlier, but clearly deviates. The incommensurate nature of the magnetic order in GdCu is further corroborated by the peak shift with temperature below .