11B NMR Study of GdB6

Abstract

NMR measurements on the 11 B were performed to determine the magnetic structures of two magnetic ordering phases of GdB 6 . The isotropic and axial hyperfine coupling constants in the paramagnetic phase were obtained to be -300 and -350 Oe/µ B respectively. In the antiferromagnetic ordering phase, nine and four kinds of the hyperfine fields at B site were observed by the 11 B-NMR and the zero field NMR at T =4.2 and 12 K, respectively. These complex hyperfine fields at B site cannot be explained by the simple magnetic structure with k =(0,0,1/2), (1/2,1/2,0) or (1/2,1/2,1/2).