Incommensurate magnetic structure of CeRhIn5
  The magnetic structure of the heavy fermion antiferromagnet CeRhIn5 is determined using neutron diffraction. We find a magnetic wave vector q_M=(1/2,1/2,0.297), which is temperature independent up to T_N=3.8K. A staggered moment of 0.374(5) Bohr magneton at 1.4K, residing on the Ce ion, spirals transversely along the c axis. The nearest neighbor moments on the tetragonal basal plane are aligned antiferromagnetically. 
Wei Bao, P.G. Pagliuso, J.L. Sarrao, J.D. Thompson, Z. Fisk, J. W.   Lynn and R. W. Erwin