Solid State Science and Technology, Vol. 14, No 1 (2006) 75-80
EFFECT OF Nd SUBSTITUTION ON ELECTRICAL TRANSPORT AND
MAGNETORESISTIVE PROPERTIES OF La2/3Ba1/3MnO3
A. Huda, S.A.Halim, S.Elias, A.A.Sidek, Z.Hishamuddin, K.P.Lim, O.J. Lee, I.Priscilla
Superconductor and Thin Films Laboratory, Department of Physics,
Faculty of Science, University Putra Malaysia,
43400 Serdang, Selangor, Malaysia
Polycrystalline semples of (La1-xNdx)2/3Ba1/3MnO3 with x = 0.0, 1/6, 1/3, ˝, 2/3, 5/6 and
1.0 have been prepared using solid state reaction. The metal-insulator transition (TP) temperatures were determined by using the standard four-point probe resistivity measurement in a temperature range of 30K to 300K. Tp shifted to lower temperatures with the increase of Nd doping. On analyzing the data by using several theoretical models, it has been concluded that the metallic (ferromagnetic) part of the resistivity (ρ) below TP fits well with the equation ρ = ρ0 + ρ2T2 + ρ4.5T4.5, indicating ρ0 is due to the grain/domain boundary effects. A second term ~ρ2T2 appears might be attributed to electron–electron scattering and second-order electron–magnon scattering term ~ρ4.5T4.5. The magnetoresistance (MR) effects are measured using the four point probe technique. The magnetoresistance defined as MR% = (Ro – RH)/RH × 100 was measured at magnetic fields H ≤ 1T at 90K, 150K, 250K and 300K. Overall, MR drops slowly when temperature rises. All doping concentration gives small variation range (~8.28% to ~56.53%). The highest MR value of ~56.53 % was measured at 1Tesla, at 100K for sample of x = 1.0. ). At Low Field Magnetoresistance (LFMR), the highest gradient of MR is 125.35% MR/Tesla for sample x=0.0 at temperature 90K. The LFMR decreases prominently with increasing doping amount, while the HFMR is increased.
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