Size Effects on Charge Transport Mechanisms and Magnetotransport Properties of Pr 0.67 Sr 0.33 MnO 3 Nanoparticles
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https://doi.org/10.1007/s11664-020-08450-x 2020 The Minerals, Metals & Materials Society
PROGRESS AND CHALLENGES WITH PEROVSKITE MATERIALS AND DEVICES
Size Effects on Charge Transport Mechanisms and Magnetotransport Properties of Pr0.67Sr0.33MnO3 Nanoparticles W. MABROUKI,1 A. KRICHENE and W. BOUJELBEN1
,1,3 N. CHNIBA BOUDJADA,1,2
1.—Laboratoire de Physique des Mate´riaux, Faculte´ des Sciences de Sfax, Universite´ de Sfax, B.P. 1171, 3000 Sfax, Tunisia. 2.—CNRS, Grenoble INP, Institut Ne´el, Universite´ Grenoble Alpes, 38000 Grenoble, France. 3.—e-mail: [email protected]
This paper covers a detailed study of the sintering temperature (TS) effect on the electrical and magnetotransport properties of Pr0.67Sr0.33MnO3 nanoparticles prepared by sol–gel method. The temperature dependence of resistivity displays a metal–insulator transition with increasing temperature. The electrical resistivity is strongly affected by particle size. The resistivity minimum at low temperature is associated to electron–electron coulombic interactions. Magnetotransport analysis was carried out using a phenomenological percolation model for all our samples. The obtained results indicate that a percolation model is not suitable for samples presenting high magnetic disorder. The magnetoresistance (MR) can be modulated by particle size effect. We have recorded considerable MR values (MR(T) = 34% at 10 K for a 1T field when TS = 850C, MR(T) = 33% at 290 K for a 2T field when TS = 1000C and MR(H) = 33% at 5 K for a 1T field when TS = 700C). The considerable MR values indicate the possibility of using these samples for several technological applications. Key words: Manganite, nanoparticle, magnetoresistance, percolation model
INTRODUCTION Manganites, with the general formula L1xAxMnO3 (L = La, Pr, Sm, … and A = Ca, Sr, Ba, Pb, …), continue to inspire researchers to understand the physics behind the magnetoresistance (MR) phenomenon.1,2 In fact, this phenomenon consists in a sharp drop in electrical resistivity induced by the presence of an applied magnetic field. Colossal MR is a property present in several technological applications like spintronics, magnetic field sensing, magnetic random-access memory (MRAM) and high-density data storage.3,4
(Received June 25, 2020; accepted August 25, 2020)
In manganites, one can detect the presence of two types of MR, intrinsic and extrinsic MR.5 Intrinsic MR is generally observed around the Curie point (TC) or in the vicinity of insulator–metal transition temperature (Tq). The intrinsic effect near the electrical/magnetic transition can be linked to an enhancement in the double-exchange mechanism and magnetic ordering near the transition. More recent studies have indicated that magnetic phase separation plays a key role in colossal MR systems,6 and extraordinary MR values can be achieved by phase-separated samples.6–12 On the other hand, grain boundaries are responsible for the extrinsic MR which can be observed over a wide temperature range below TC/Tq and can be ascribed to spinpolarize
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