Anomalous magnetoresistance behavior ofR2Ni3Si5

Abstract

Magnetoresistance ͑MR͒ measurements on the antiferromagnetically ordered polycrystalline R 2 Ni 3 Si 5 ͑R ϭ Pr, Dy, Ho; T N ϭ 8.5 K, 9.5 K, 6.0 K, respectively͒ 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 field dependence and persisting even above the magnetic ordering temperature, is observed, which is unusual. Temperature dependence of MR ͑in a constant high field͒ 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. ͓S0163-1829͑96͒05834-1͔The members of the R 2 Ni 3 Si 5 ͑R ϭ rare earths͒ series exhibit many unusual and interesting magnetic, electrical, and thermal properties. For example, in Ce 2 Ni 3 Si 5 and Eu 2 Ni 3 Si 5 , the rare earth ions are in valence fluctuating state, 1,2 Tb 2 Ni 3 Si 5 shows a double magnetic transition, 3 and magnetic ordering temperatures of many of the members of this series do not follow the well established deGennes scaling. [3][4][5] In order to understand the nature of magnetic interaction in these materials, we have carried out magnetoresistance ͑MR͒ measurements. Here we report our MR results on R 2 Ni 3 Si 5 ͑R ϭ Pr, Dy, Ho͒ which exhibit an anomalous temperature and field dependence.The synthesis and preliminary magnetic properties of R 2 Ni 3 Si 5 ͑R ϭ Pr, Dy, Ho͒ have been reported earlier. 3,5,6 These compounds crystallize in orthorhombic U 2 Co 3 Si 5 -type structure ͑space group Ibam͒. 6 The compounds Pr 2 Ni 3 Si 5 , Dy 2 Ni 3 Si 5 , and, Ho 2 Ni 3 Si 5 order antiferromagnetically with T N ϭ 8.5 K, 9.5 K and 6 K, respectively. High temperature susceptibility follows a Curie-Weiss ͑CW͒ behavior, with a magnetic moment close to the respective free trivalent R moment.Field dependence of MR, ⌬ / (0)"ϭ͓ (H)Ϫ (0)͔/ (0), where (H) is the resistivity measured at magnetic field H…, for Pr 2 Ni 3 Si 5 , Dy 2 Ni 3 Si 5 and Ho 2 Ni 3 Si 5 at different temperatures is shown in Figs. 1, 2, and 3, respectively. An expanded plot of magnetoresistance and magnetization at 6K for Ho 2 Ni 3 Si 5 at low field ͑0-5 kOe͒ is given in Fig. 4 for clarity. For the sake of comparison, MR of Y 2 Ni 3 Si 5 ͑where no magnetic effects associated with R ions are expected as Y is nonmagnetic͒ is also presented here ͑Fig. 5͒.The salient features of MR, common to all the three materials, Pr 2 Ni 3 Si 5 , Dy 2 Ni 3 Si 5 , and Ho 2 Ni 3 Si 5 , are described below taking Dy 2 Ni 3 Si 5 as a typical example ͑Fig. 2͒. ͑a͒ Below the magnetic ordering temperature ͑T N ϭ 9.5 K͒, MR first increases with increasing field, reaches a maximum (ϳ8%͒ at 12 kOe ͑at 4.4 K͒, then decreases and reaches a minimum around 35 kOe and then o...

Magnetism and transport studies in off-stoichiometric metallic perovskite compounds GdPd3Bx (x=0.25, 0.50 and 0.75)

“…9(b)). A similar behavior was earlier observed in the case of Dy 2 Ni 3 Si 5 [17], where the observed maxima in the MR(H) was attributed to the metamagnetic transition occurring at the same field in the isothermal magnetization measurement [17]. However, in the case of GdPd 3 B 0.75 we do not observed any evidence of such metamagnetic transition in isothermal magnetization measurement and M varies linearly with H for H 41 T (Fig.…”

Magnetic and transport properties of Pr2Pd3Si5

“…5). As seen with an increase in temperature the magnetoresistance decreases right up to the transition temperature above which it starts increasing showing a broad hump with maximum at 26 K. The peak near 26 K may be associated with the crystal field effect as the specific heat data suggests the first excited state to be at 28 K. A similar peak in temperature dependence of magnetoresistance has also been observed in Pr 2 Ni 3 Si 5 , Dy 2 Ni 3 Si 5 and Gd 2 Ni 3 Si 5 where it was explained in terms of long lived ferromagnetic correlation above the transition temperature [9,10]. It was argued that on decreasing the temperature the phonon mediated resistivity decreases causing the magnetoresistance to increase, reaches to a maximum peak below which magnetoresistance starts decreasing due to the contribution from short-range ferromagnetic correlations.…”

Valence fluctuation in Ce2Co3Ge5 and crystal field effect in Pr2Co3Ge5

“…For example, literature show pressure-induced superconductivity in Kondo antiferromagnet Ce 2 Ni 3 Ge 5 [9,10], valence fluctuation in Ce 2 Ni 3 Si 5 [11] and anomalous magnetoresistance in R 2 Ni 3 Si 5 (R ¼ Pr, Dy, Ho) [12]. Ce 2 Pd 3 Si 5 [13], Ce 2 Rh 3 Ge 5 and Ce 2 Ir 3 Ge 5 [14] are known antiferromagnetic Kondo lattice systems with moderate heavy-fermion behavior in the last two compounds.…”