Itinerant magnetism in Kondo crystal CeB6 as indicated by polarized neutron scattering

A magnetic Bragg reflection corresponding to the wave vector k 13 = (2 p / a )[1/2,1/2,1/2] of the antiferro-quadrupolar ordering is found in CeB 6 in zero magnetic field below the Néel temperature T N . Its intensity is two orders of magnitude weaker than those due to the basic magnetic structure [O. Zaharko et al. , Phys. Rev. B 68 , 214401 (2003)]. The peak has a width of the other Bragg reflections below T N , but widens abruptly at T = T N with simultaneous increase of intensity. Correlation length just above T N is of the order of 70 Å. The peak intensity decreases to zero at T » 7 K with no visible anomaly at the antiferro-quadrupolar ordering temperature T Q = 3.3 K. The features of this magnetic ordering are typical for the itinerant magnetism with 5 d electron of Ce 3+ [Yu.S. Grushko et al ., phys. stat. sol. (b) 128 , 591 (1985)] being involved.