Anomalous magnetoresistance behavior of R(2)Ni(3)Si(5) (R=Pr,Dy,Ho)

Magnetoresistance (MR) measurements on the antiferromagnetically ordered polycrystalline R(2)Ni(3)Si(5) (R = Pr, Dy, Ho; T-N = 8.5 K, 9.5 K, 6.0 K, respectively) materials are reported here. Field dependence of MR, measured both below and above their respective ordering temperatures and up to a field of 45 kOe, is found to be anomalous. In all the three cases, in the magnetically ordered state, MR is not monotonic but exhibits a maximum and a minimum. A considerable contribution to MR, with nearly linear held dependence and persisting even above the magnetic ordering temperature, is observed, which is unusual. Temperature dependence of MR (in a constant high field) above the magnetic ordering temperature, measured up to 100 K, exhibits a pronounced hump. The behavior of magnetoresistance at low temperatures is interpreted in terms of metamagnetism along with a short range ferromagnetic interaction.