Phase transition between the itinerant and the localized antiferromagnetic orders in Ce(Ru0.9Rh0.1)2(Si1-yGey)2

Abstract We have studied on the shift of the itinerant-electron-type magnetic order (SDW) to localized-electron-type antiferromagnetic order (LAF) in the heavy fermion system Ce ( Ru 0.9 Rh 0.1 ) 2 ( Si 1 - y Ge y ) 2 . The strength of the cf-hybridization in Ce ( Ru 0.9 Rh 0.1 ) 2 Si 2 is reduced by substituting Ge for Si. The electrical resistivity of the y = 0.3 sample shows a sharp downturn anomaly at T N indicating that the magnetic order of this compound is of the LAF. On the other hand, in the samples with y ⩽ 0.2 , the resistivity shows an sharp upturn anomaly at T N supposedly due to the energy gap at the Fermi surface associating with the onset of the SDW. The most remarkable result is that for y = 0.26 the resistivity shows both of the downturn and the upturn anomaly in the same sample, which strongly indicates a first-order phase transition between the LAF order and the SDW order.