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

Abstract

ARTICLES YOU MAY BE INTERESTED INSurface spin glass and exchange bias effect in Sm 0.5 Ca 0.5 MnO 3 manganites nano particles AIP Advances 1, 032110 (2011); https://doi.org/10.1063/1.3623428The effect of inserted layers on the anomalous Hall effect and perpendicular magnetic anisotropy in Ta In this paper, we have studied low-temperature magnetic properties and transport dynamics of half-doped Pr 0.5 Sr 0.5 MnO 3 (PSMO) nano-manganite. Nanoparticles with different average grain sizes are synthesized using chemical pyrophoric reaction route and exhibit same crystal structure. It is reported that particle size reduction in half-doped PSMO manganite interestingly leads to ferromagnetic (FM) metallic behavior which is accompanied by coupled positive magnetoresistance (PMR) (up to 9%) at fields (H ≤ 1kOe at 50K) and negative magnetoresistance (NMR) (∼59% at 100K) at 80kOe fields. Interestingly, maximum PMR is appeared at much lower than the critical field (30kOe) for the melting of insulating -antiferromagnetic (AFM) ordered state. Moreover, it is found that low-temperature AFM-FM phase transition, T N ∼ 135K is smeared out with reduction of particle size; however, the transition is prominent in bulk material. A metastable magnetic state with a mixed fraction of FM and AFM phases is observed below T N . Superparamagnetic (SPM) behavior of PSMO nanoparticles has been revealed by probing ac-susceptibility measurements. Lowtemperature transport dynamics has been investigated through four probe resistivity and magneto-transport measurements. A size-induced insulating-metallic phase transition is observed on nano dimension in the range of 125-155K under high magnetic fields; however, the bulk counterpart remains insulating over the entire temperature range. The non-trivial electronic-and magnetotransport properties are explained by the inter-grain spin-polarized hopping mechanism through double exchange (DE) interactions. These issues have been revisited and discussed in the framework of enhanced surface disorder, where surface spins plays the crucial role for inter-grain transport dynamics in nanometric dimension. We believe the present field dependent MR holds excellent potential for future spintronic devices and manifests the exotic properties of strongly correlated materials. © 2018 Author(s)

Structural and critical properties of Pr0.5Sr0.5MnO3 nanoparticle

“…These suggest that the structural system of PSMO-NP is the tetragonal one. It means that the structure of PSMO does not change when the crystalline size is reduced to the nanometer scale, which is in good agreement with that reported by Das et al [19] about the structure of nano and micro-sizes of PSMO.…”

“…It is easy to see that the magnetic phase transition in a range of 146-161 K is the first-order, whereas the magnetic phase transition around T C = 237.5 K is the second-order, according to Banerjee's criteria [35]. A similar result about the nature of the magnetic phase transitions of PSMO single crystal and nano-micro particles was also observed by Bingham [30] and Das [19], respectively.…”

“…In this refinement, the lattice parameters and the cell volume are 7) Å 3 , respectively. A similar result was reported by Das et al for PSMO bulk sample [19]. The Williamson-Hall method using the full width at half maximum of XRD lines [22][23][24] has been used to determine the average crystalline size (<D>) for PSMO-NP sample.…”

“…A slight decrease of the experimental (μ eff ) value compared with that calculated for the case of only contribution from the effective magnetic moments of Mn 3+ and Mn 4+ ions (m eff sp ) could be related to the surface magnetic disorder effect on PSMO particles. Therefore, the correlation between the magnetic moments in the PM phase is reduced [19].…”

“…According to recent studies, the grain size or crystalline size is a very important factor, which strongly influences the physical properties of materials. The influence of size effect on the structure, electrical and magnetic properties of manganites synthesised by different methods has been extensively studied [13][14][15][16][17][18], but there are still controversial issues related to the nature of magnetic interactions and the critical behaviour in manganites (namely PSMO [19,20]) that need to be resolved. In this work, we give some results and discussions on the structure and the critical behaviour of a Pr 0.5 Sr 0.5 MnO 3 nanoparticle (PSMO-NP) sample with an average crystalline size of <D> = 58 ± 2 nm fabricated by a combination of reactive milling and heat treatment methods, a simple method can be applied to fabricate nanoparticle manganites.…”