Enhanced Low-Field Magnetoresistance in La_0.71Sr_0.29MnO₃ Nanoparticles Synthesized by the Nonaqueous Sol–Gel Route

Abstract

In colossal magnetoresistive (CMR) materials, magnetic fields of several tesla are typically required to exhibit large changes in electrical resistance, and hence, materials should be engineered to provide a more sensitive MR response at lower fields for their viability in practical applications. Enhanced low-field magnetoresistance (LFMR) was observed in highly ferromagnetic ∼20 nm La 0.71 Sr 0.29 MnO 3 particles synthesized by the nonaqueous sol−gel route. The enhanced LFMR of the nanoparticles (NPs) reaches 29.8% at 30 K with 50 mT, and the high-field magnetoresistance was 56% with a 5000 mT applied field. The large LFMR effect can be attributed to the spin-polarized tunneling across the ∼1.3 nm thick natural grain boundaries. The weaker MR effect below 30 K was attributed to the re-entrant spin glass at the core of the NPs and surface spin glass phase that could be eliminated with lower and higher applied fields, respectively. The magnetic and MR properties of the NPs were compared to those of the corresponding ∼2 μm bulk material with the same elemental composition. These results provide insight into the role of particle size, grain boundaries, and spin glass phases on the MR properties, and the consequence of this finding is useful for the potential fabrication of LFMR devices.

Emergence of ferromagnetism and metallicity in Pr0.5Sr0.5MnO3 nanoparticles

“…By lowering the temperature, AFM ordering is increased significantly, and the core regime becomes broader, resulting in the less value in MR. Recently, similar kind of MR characteristics has been observed by Evetts et al 33 and Sadhu et al 34 Low field magnetoresistance (LFMR) behavior for PSMO 1150 and PSMO 850 samples are shown in the inset of Figs. 6(c) and 6(d), respectively.…”

“…It is reported that MR in manganite can be controlled by many factors especially spin disorder, non-collinear spin. 33,34,39 Finite magneto-resistance for all samples signify notable drop down in resistivity with an increase of applied field and promotes FM ordering in the compound by suppression of AFM ordered state. 40,41 In polycrystalline manganite, magneto-resistive property strongly depends on intrinsic part (MR INT ) (originates through DE interaction between two neighboring Mn ions), and intergranular spin-polarized tunneling (MR SPT ).…”

Large, Temperature‐Tunable Low‐Field Magnetoresistance in La0.7Sr0.3MnO3:NiO Nanocomposite Films Modulated by Microstructures

“…[ 26 ] It is notable that the spin pinned effect occurs at the nanosized grain surface defect sites or spin coupling at the boundaries. [ 26,27 ] In addition, the short range ferromagnetic (FM) coupling order may add the opportunity of spin scattering even near the Curie temperature. [ 28,29 ] Thus it is speculated that the high-temperature LFMR in LSMO composite fi lms can be got through tuning the grain size and the FM coupling at the phase boundary.…”

Synthesis and Characterization of La0.8Sr0.1Ag0.1MnO3 Nano Perovskite Compound

“…8 2 ) were taken in stoichiometric proportion and were dissolved in deionized water with subsequent addition of Citric acid and Ethylene Glycol. Afterwards, the monohydrate Citric acid and the Ethylene Glycol were added to ensure the homogeneity and the transparency of the solution.…”

“…or monovalent alkaline metal ion, Na, Ag, K,…), have spurred considerable scientific and technological interest in recent decades due to their remarkable magnetic, electric transport, catalytic and colossal magnetoresistance (CMR) properties, etc. [1][2][3].…”